PLACE ll RETURN BOX to mncvc this checkout from your record. TO AVOID FINES "mm on or bdon dd. due. DATE DUE DATE DUE DATE DUE .J 164 “i. L__I .l______ i! ll *fl— fl“ MSU I. An Affirmative ActionlEqml Opponunlty Instittuion MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS By Man-Lai Lee A DISSERTATION Submitted to Michigan State University in partiai fulfiiiment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Food Science and Human Nutrition 1990 905497< ABSTRACT MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS By Man-Lai Lee Meat flavor generation in extruded soy protein products via pre-extrusion addition of flavor precursors was investigated. The extrudates were comparatively examined for their sensory properties, volatile components, and their application in ground beef loaves. The synthetic meat flavors (HH, SW) thermally generated from flavor precursor systems were found to be superior to the commercial beef samples (BV, MM, H0, GG) and comparable to the natural beef flavor (BE). The dominant nonmeaty aroma qualities of HH, HO, and BE, were "Toasted/Burnt", "Spicy/Fragrant" and "Cooked Vegetables", and "Flat/Dull", respectively and were higher than ideally desirable. The precursor system of HH and H0 were selected for subsequent extrusion study. The pre-extrusion addition of flavor precursors in the soy extrudate (15HH) resulted in a moderate, but significant improvement in "Meaty" flavor when compared to the unflavored product (UFC). No difference in meatiness was found between 15HH and the commercial beef flavored extrudate (15H0). Neither flavor systems was entirely successful in masking the Off-flavors of soy protein products. Except for saltiness, no differences in "Roasted", "Sweet", "Green", "Beany" and "Bitter" notes were found among the extrudates. They were scored lower in "Meaty” flavor but higher in "Green"/"Beany" notes than ideally desirable. Subtle differences in some physicochemical Man-Lai Lee properties were observed among the samples. By gas chromatography-mass spectrometry, the volatile components of 15HH (59 identified) was found to consist mainly of aldehydes, ketones, thiols, and pyrazines, of UFC (55) was predominantly pyrazines, and of HH (29) was aldehydes, alcohols, and acids. When compared to UFC, substantial increases in 2-/3-methylbutanal, 2-pentanone, and dimethyl- trisulfide and the generation of several new heterocyclics were evident in 15HH and their implications to the perceived meaty flavor were discussed. When compared to the UFC-substituted products, substitution with 15HH at 30-60% had a significantly positive effect on the aroma and color, but a limited effect on the flavor of ground beef loaves. The juiciness and mouthfeel of the products were adversely affected by increasing levels of soy-substitution. In contrast to the all-beef control, all soy-substituted products had higher cooking yields and moisture, lower fat, and enhanced oxidative stability. Dedicated to my daughter, Samantha iv ACKNOWLEDGMENTS To my advisor, Dr. J.I. Gray, my heartfelt thanks for his conceptual assistance, guidance, and friendship throughout my graduate study. To my co-advisor, Dr. A.M. Pearson, my genuine appreciation for his many critical but constructive comments. A special "thank you" is extended to my committee members: Dr. J.F. Price (Department of Food Science and Human Nutrition), Dr. D.R. Dilley (Department of Horticulture), and Dr. G.L. Hosfield (Department of Crop and Soil Sciences) for reviewing this manuscript. Grateful appreciation is due to Dr. E. Anderson and Mr. T. Gaylord of Kellogg's Company (Battle Creek, MI), and Dr. B. Musselman (formerly) and Miss E. Baltzer of the Department of Biochemistry for their expertise in the operation of the GC/MS and data processing systems, to Mr. B. Vibbert of Gerber Products Company (Fremont, MI) for his skillful operation of the extruder, to Central Soya Company (Fort Wayne, IN) for supplying the defatted soy flour, to the Department of Food Science and Human Nutrition for financial assistance, to my friends, Touran, Naiyini, Arun, and Susan, for their stimulating discussions and comradeship. Most importantly, I would like to thank my husband and family for their love, understanding, and moral support which made possible the completion of this work. TABLE OF CONTENTS Page LIST OF TABLES .......................... x LIST OF FIGURES ......................... xii INTRODUCTION ........................... 1 LITERATURE REVIEW ........................ 4 Off-flavors in Soy Protein Products ............. 4 Green, Grassy and Beany Flavor .............. 6 Bitter Taste ....................... 8 Cooked Soybean Odor ................... 10 Sweet Taste ....................... 10 Burnt Flavor ....................... 10 Contaminant Flavors ................... 11 Flavor Binding in Soy Protein Products ............ 13 Soy Protein-flavor Interactions ............. 13 Flavor Release in Soy Protein Products .......... 20 Chemistry of Meat Flavor: An Overview ............ 21 Maillard Reaction Products and Meat Aroma ........ 23 Factors Affecting the Maillard Reaction ....... 24 Reaction Mechanisms ................. 25 Its Role in Meat Aroma Production .......... 26 Beef Flavor Volatiles .................. 40 Chemical Nature and Relative Contribution of Volatiles to Cooked Beef Aroma ........... 68 Comparison of Beef and Soy Volatiles ......... 73 Flavoring Textured Soy Protein Products ........... 75 Meat Flavor System .................... 75 Methods of Flavoring ................... 77 Post-extrusion Flavor Addition ............ 78 Pre-extrusion Flavor Addition ............ 78 Pre-extrusion Addition of Flavor Precursors ..... 80 References .......................... 81 CHAPTER I. COMPARATIVE AROMA ASSESSMENT OF SELECTED MEAT/BEEF FLAVORS ....................... 97 ABSTRACT ............................. 97 INTRODUCTION ........................... 98 vi Page EXPERIMENTAL ........................... 100 Selection of Meat/Beef Flavors ................ 100 Preparation of Meat/Beef Flavors ............... 100 Synthetic Meat Flavors .................. 100 Commercial Beef Flavors ................. 104 Natural Beef Flavor ................... 104 Presentation of Meat/Beef Flavors .............. 105 Experimental Designs and Sensory Methodology ......... 106 General Aroma Assessment ................. 106 Descriptive Aroma Evaluation ............... 106 Sensory Panel .................... 107 Statistical Analyses ..................... 107 RESULTS AND DISCUSSION ...................... 108 General Aroma Assessment ................... 108 Descriptive Aroma Evaluation ................. 112 CONCLUSIONS ........................... 116 REFERENCES ............................ 117 CHAPTER II. MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN EXTRUDATES. I. SENSORY EVALUATION ......... 119 ABSTRACT ............................. 119 INTRODUCTION ........................... 120 EXPERIMENTAL ........................... 122 Material ........................... 122 Defatted Soy Flour .................... 122 Flavor Systems ...................... 122 Model System Study ...................... 122 Preparation ....................... 123 Ranking Test ....................... 124 Extrusion Study ....................... 125 Preblending Flavor Systems with Defatted Soy Flour. . . . 125 Extrusion Process .................... 125 Chemical/Physical Analyses .................. 127 Sensory Evaluation ...................... 128 RESULTS AND DISCUSSION ...................... 130 Chemical/Physical Analysis .................. 130 Browning Index (81) ................... 130 pH ............................ 132 Moisture ......................... 132 Fat ........................... 132 Sensory Evaluation ...................... 133 "Green“ and "Beany" ................... 133 vii Page "Meaty" and "Roasted" ................... 137 "Sweet", "Salty", and "Bitter" .............. 138 GENERAL COMMENTS ......................... 140 REFERENCES .................... ‘ ........ 142 CHAPTER III. MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS. II. CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRIC ANALYSIS OF VOLATILE COMPONENTS. . . . 145 ABSTRACT ............................. 145 INTRODUCTION ........................... 147 EXPERIMENTAL ........................... 149 Sample Sources and Descriptions ................ 149 Isolation and Concentration of Volatile Components ...... 149 Volatile Isolates of Soy Extrudates (HH and UFC) ..... 149 Volatile Isolate of Synthetic Meat Flavor (HH) ...... 150 Blank Volatile Isolates .................. 150 Capillary Gas Chromatography-Mass Spectrometry (GC-MS) . . . . 150 RESULTS AND DISCUSSION ...................... 152 Synthetic Meat Flavor (HH) vs Flavored Soy Extrudate (15HH). . 168 Flavored Soy Extrudate (15HH) vs Unflavored Soy Extrudate (UFC) ............................ 171 GENERAL COMMENTS ......................... 176 REFERENCES ............................ 178 CHAPTER IV. MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS. APPLICATION OF FLAVORED AND UNFLAVORED SOY EXTRUDATES IN GROUND BEEF LOAVES. . . ._ ....... 184 ABSTRACT . . .. .......................... 184 INTRODUCTION ........................... 185 EXPERIMENTAL ........................... 187 Preparation of Ground Beef Loaves .............. . 187 Food Materials ...................... 187 Preparation ........................ 187 Proximate Analyses ...................... 189 Sensory Evaluation ...................... 190 Oxidative Stability ...................... 190 Statistical Analyses ..................... 190 viii Page RESULTS AND DISCUSSION ...................... 191 Proximate Analyses ...................... 191 Cooking Characteristics ................... 194 Sensory Evaluation ...................... 196 Oxidative Stability ..................... 199 CONCLUSIONS . . . L ....................... 202 REFERENCES ............................ 204 SUMMARY AND CONCLUSIONS ..................... 207 FUTURE RESEARCH ......................... 209 APPENDIX. Mass Spectra of Some Meat Flavor Volatiles ...... 211 ix LIST OF TABLES Table LITERATURE REVIEW 1 Compounds that produce green-beany flavor in soy protein products: their contributions and flavor thresholdsa. . . . 2 Origin, nature, and control of off-flavors in soy protein products .......................... 3 Taste threshold values in meat flavor componentsa ..... 4 Chemical compounds and odor descriptions of beef and soy flavor volatiles ...................... 5 Compounds possessing meaty notes .............. CHAPTER I 1 Chemical compositions of flavor precursors Of synthetic meat flavors ........................ 2 Characteristic features and formulations of synthetic, commercial, and natural meat/beef flavors ......... 3 Meaty aroma ratings and general comments on aroma qualities of synthetic, commercial, and natural meat/beef flavors . . 4 Intensity scores of six major aroma descriptors for an "Ideal" and three selected meat/beef flavors ........ CHAPTER II 1 Chemical composition of model systems ........... 2 Comparisons of some chemical/physical data of an unflavored (UFC) and flavored (15HH and 15H0)a soy extrudate ..... 3 Comparisons of the sensory intensity scores of an "Ideal" meat flavored (IMF), an unflavored (UFC), and flavored (15HH and 15H0)a soy extrudates .............. CHAPTER III 1 Volatile components (identified in synthetic meat flavor (HH), flavored soy extrudate (15HH), and unflavored soy extrudate ......................... Page 12 20 41 72 101 102 109 113 123 131 134 153 Table 2 Page A summarized comparison of relative percent abundances of the major classes of volatile components identified in synthetic meat flavor (HH), flavored soy extrudate (15HH), and unflavored soy extrudate (UFC) ............. 166 CHAPTER IV 1 Ingredients of ground beef loaves substituted with/without flavored and unflavored soy extrudates ........... 188 Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the moisture and fat contents of raw and cooked ground beef loaves ....... 192 Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the cooking losses of ground beef loaves ..................... 195 Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the sensory ratingsa of ground beef loaves ..................... 197 xi LIST OF FIGURES Figure LITERATURE REVIEW 1 Off-flavors in soy protein products from linoleic or linolenic acids as catalyzed by lipoxygenase ........ 2 Sugar-amine (Maillard) browning reactions: Two pathways to melanoidins and by-products ................ 3 Parent structures of some heterocyclics .......... 4 Some simple reactions of Amadori products ......... 5 Formation of furan derivatives from glucose Amadori products .......................... 6 Formation of maltol and derivatives from Maillard reaction. 7 Formation of alkyl-5H-6,7-dihydroxycyclopenta[b]-pyrazines from Maillard reaction products .............. 8 Formation of pyrrolo [1,2-a] pyrazines ........... CHAPTER II 1 Aroma and flavor-by-mouth difference scores between soy extrudat(s) and IMF (A and B), and flavored extrudate(s) and unflavored extrudate (C and D) ............. CHAPTER III - 1 Reconstructed ion chromato rams of the volatile isolates of (a) synthetic meat flavor THH), (b) flavored soy extrudate (15HH), and (c) unflavored soy extrudate (UFC) ....... CHAPTER IV 1 Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the TBA numbers of ground beef loaves stored at ~4°C for up to 6 days ..... xii Page 25 27 28 3O 31 36 37 136 163 200 INTRODUCTION Textured soy protein products (TSPs) are protein-rich items that have been modified in appearance, texture and flavor to simulate conventional foods, especially meat items (Kinsella, 1983). They are available today as extruded granules or chunks, spun fibers, and heat-coagulated protein pieces (Wolf, 1970; Ritter, 1978; Kinsella, 1983). It is estimated that 95% of TSPs are currently made by the extrusion process (Kinsella, 1983). Therefore, it is generally assumed that TSPS PETE? t0 StVUCtUVEd protein products produced by various extrusion processes. Basically, extrusion involves metering moistened proteinaceous material via a screw, through a heated barrel ending in a restricted aperture termed a die. During extrusion, proteinaceous material is cooked and plasticized by a combination of pressure, heat, and mechanical shear. Extrudate emerging from the die undergoes an exothermic expansion yielding a relatively dry, porous product which assumes a chewable texture upon hydration in water (Williams et al., 1977). TSPs are widely used as meat extenders in comminuted meat items (such as sausages, frankfurters, and bologna), and other meat products (for example, meat patties, meat loaves, and salisbury steak) (Kinsella, 1983). Advantages of extending ground meat with TSPs include lower fat content, increased moisture retention, improved 2 tenderness, reduced shrinkage during cooking, inhibition of rancidity, and considerably lower cost (Schweigert, 1974; Langsdorf, 1981; Berry et al., 1985; kotula and Berry, 1986). Because of these beneficial prOperties, the USDA's National School Lunch Program has permitted the use of up to 30% of hydrated TSP with 70% of ground meat as an acceptable meat alternative since 1971 (Rakosky, 1974; Bodwell, 1983). Hammonds and Call (1970) forecasted that TSPs would account for 10% of domestic meat consumption, that is, around 2 billion lbs/year by 1985. In 1972, it was predicted that 2 to 4 billion lbs of hydrated ground meat extenders would be in use by 1980 (Bird, 1974). In retrospect, this prediction was grossly over-inflated, and since 1972, there has been relatively little movement in volume (Kinsella, 1983). The major factor preventing the widespread use of TSPs as meat extenders has been attributed to its unsatisfactory flavor (Cowan, 1973; Sutton, 1978; van den Ouweland and Schutte, 1978; Rackis et al., 1979; Kinsella, 1983; Kinsella et al., 1985). Soy protein products often have a characteristic off-flavor, which has been described as green/grassy and beany. When the meat formulation is prepared with insufficient seasonings to mask the off-flavors, consumers often find these foods objectionable (Kinsella, 1983). This research was undertaken to investigate the use of thermal extrusion of defatted soy flour containing meat flavor precursors as a means of improving the flavor of soy protein products. This study was based on the hypothesis that since extrusion uses heat, the flavor precursors should react during processing to produce the desirable 3 flavor components. The Objectives of this study were: (a) To select a meat flavor precursor system for the extrusion study by sensorially evaluating the aroma qualities of selected meat/beef flavors; (b) To investigate the effects of pre-extrusion addition of meat flavor precursors on the sensory prOperties of soy extrudate; (c) To examine the effects of added meat flavor precursors on the formation of desirable flavor components in soy extrudate; and (d) To evaluate the application of the flavored soy extrudate on the quality characteristics of ground beef loaves at increasing levels of soy-substitution. LITERATURE REVIEW Soy proteiN products (SPPs) (soy flours/grits, concentrates and isolates), particularly, textured soy protein products (TSPs), have received major attention as potential substitutes for meat proteins (Kinsella, 1983). However, flavoring is still a major obstacle to more widespread use Of SPPs (Kinsella, 1983). Meat flavors added to TSPs as meat extenders/analogs must not only impart the desired positive meat-like flavor while allowing for uneven adsorption or release during processing, storage and consumption, they must also mask the formidable assortment of off-flavors associated with SPPs (van den Ouweland and Schutte, 1978; Heinze et al., 1978; Schutte and van den Ouweland, 1979; Kinsella and Damodaran, 1980; Palkert, 1980; Kinsella, 1983). Due to the diversity of the aforementioned subjects, this review will attempt only to cover the pertinent information and significant/ current findings of these interrelated tOpics. Off-flavors in Soy Protein Products Numerous authors have reviewed the off-flavors present in SPPs (Maga, 1973; Cowan et al., 1973; Wolf, 1975; Eskin et al., 1977; Sessa and Rackis, 1977; van den Ouweland and Schutte, 1978; Heinze et al., 1978; Rackis et al., 1979; Kinsella and Damodaran, 1980; Kinsella, 1983). Thus far, there has been only one published sensory and 5 analytical report which examined the compounds responsible for off- flavors in TSPs (Palkert, 1980). Generally, it is assumed that the off-flavors of TSPs and soy flours are identical and derived from the same compounds. Some of the off-flavors in SPPs are associated with the carbonyls and scission products of the hydroperoxides formed via the action of lipoxygenase on polyunsaturated fatty acids, especially linoleic and linolenic acids (Wolf, 1975; Sessa et al., 1979; Rackis, 1979; Kinsella and Damodaran, 1980). ALDEHYDES KETONES 1 ALCOHOLS FURANS LIPOXYGENASE x” LINOLEIC OR > HYDROPEROXIDES —»a- or y-KETOLS LINOLENIC ACID \. EPOXIDES_ TRIHYDROXY ACIDS Figure 1. Off-flavors in soy protein products from linoleic or linolenic acids as catalyzed by lipoxygenase (adapted from Kinsella and Damodaran, 1980). The descriptors most commonly associated with off-flavors in SPPs are green/grassy, beany. and bitter (Kalbrenner et al., 1971). Processing may accentuate or cause the development of off-flavors described as toasted, astringent, cardboardy and mealy (Kalbrenner et al., 1971). Other off-flavors which have been noted in SPPs include sweet, cooked soybean, burnt, catty, and fusel (Schutte and 6 van den Ouweland, 1979). The important sensory notes in TSPs are beany, cereal, and roasted (aroma), and cereal, beany, and sweet (flavor) (Palkert, 1980). These descriptors are listed in order of importance. Green, Grassy and Beany Flavor It is generally felt in the food industry that green, grassy and beany flavor of TSPs is perhaps its most important flavor defect (Palkert, 1980). This off-flavor apparently arises primarily from the oxidation of linoleic acid in the soy flour (Rackis et al., 1979). ISOpentanol, hexanol, heptanol, hexanal, cis-3-hexenal, 25heptenal, 2,4-decadienal, ethyl vinyl ketone, n-pentylfuran, cis- and trans-Z-(l-pentenyl)furan have all been credited with contributing to the green/beany flavor of SPPs (Goossens, 1974; Dutton, 1978; Rackis et al., 1979; Kinsella and Damodaran, 1980) (Table 1). During thermal processing, cis-3-hexenal can readily isomerize to trans-3-hexenal which possesses an oily grassy flavor (Sessa and Rackis, 1977). The flavor thresholds of the contributors to green/beany flavor in SPPs are presented in Table 1. These values may be an order of magnitude less when tested in a non-oily medium (Rackis et al., 1979; Kinsella and Damodaran, 1980). For example, Kinsella (1969) reports a 3-fold difference in flavor threshold values of cis-3-hexenal in Oil (0.15 parts per million (ppm)) versus milk (0.05 ppm) and a 25-fold difference for trans-2-hexenal with 2.5 ppm in oil versus 0.1 ppm in skim milk. The threshold value for the grassy, beany flavor associated with raw defatted soy flour in aqueous dispersion is approximately 300 ppm (Kalbrenner et al., 1971) which seems high, but may reflect its 7 Table 1. Compounds that produce green-beany flavor in soy protein products: their contributions and flavor thresholdsa. Threshold (ppm in oil) Compound Flavor Description Odor Taste Reference n-Hexanal Green, grassy 0.32 0.15 Grosch (1975) cis-3-Hexenal Green, grassy 0.11 0.11 Chang et al. (1966) Ethyl vinyl Green, beany 5(milk) Mattick and ketone Hand (1969) n-Pentylfuran Beany 2 1-10 Chang et al. (1966) 2-(cis-1- Beany 8 8 Ho et al. (1978) Pentyl)furan 2-(trans-1- Beany 1 1 H0 at al. (1978) Pentyl)furan n-Pentanol Arai et al. (1970) Isopentanglb n-Hexanol n-Heptanol aAdapted from Rackis et al. (1979). Postulated to contribute or enhance the green-beany flavor of soy protein products. binding to the protein. Although the triglycerides in soybeans undergo considerable transformation in composition during maturation, the characteristic green, grassy, and beany flavor does not vary in intensity (Rackis et al., 1972). This would indicate that minimal oxidation of the highly unsaturated lipids by lipoxygenase may be enough to initiate formation of this flavor. Recently, supercritical carbon dioxide (SC-C02) has been used in the extraction of soybeans and full-fat soy flakes (Friedrich et al., 1982, 1984; Friedrich and Eldridge, 1985; Eldridge et al., 1986). The usual grassy, beany and bitter flavors of hexane-defatted soy flours were only minimally detectable in the optimally SC-COZ (at least 375 kgf/cm2 about 85°C, and moisture levels of 10.5 to 11.5%) extracted materials (Eldridge et al., 1986). Conditions could be selected to produce defatted soy flours with acceptable nitrogen solubility indices (>70%) and flavor scores (>6.5 on a scale of 1-strong to 10-bland) (Eldridge et al., 1986). Bitter Taste An intensely bitter taste developed when oil-free soy phosphatides were irradiated with ultraviolet light (Sessa et al., 1969). Purified soy phosphatidylcholine (SPC) oxidized in an aqueous suspension developed a bitter taste, whereas hydrogenated SPC similarly treated did not (Sessa et al., 1974). The bitter threshold level of oxidized SPC in charcoal-filtered tap water was calculated to be about 60 ppm (0.006%). 9 Three oxidized SPCs designated SPC-A, SPC-B, and lyso-SPC were isolated from the residual lipids of hexane-defatted soy flakes (Sessa et al., 1976). A seven-member taste panel found that 0.05% suspensions of SPC-B and lyso-SPC from defatted flakes stored 1 year at 4°C were strongly bitter, whereas SPC-A was rated weakly bitter (Sessa et al., 1976). Based on the above studies and the fact that defatted soy flakes contain at least 0.08% oxidized SPC, Sessa et al. (1976) concluded that oxidized phospholipids was a major cause of the bitter taste of SPP. Oxygenated (keto, epoxy, hydroxy) derivatives of fatty acids isolated from lipoxygenase-catalyzed oxidationtrflinoleic acid (Bauer and Grosch, 1977) and dimers formed from acylhydroperoxides also impart a bitter taste. Taste threshold of the various unsaturated tri- and tetrahydroxy derivatives are in the range of 200-1500 ppm (Bauer and Grosch, 1977). The presence of a double bond in these polyhydroxy acids enhances the bitter taste three-fold (Bauer and Grosch, 1977). Since SPC contains a complex mixture of oxygenated fatty acids (Sessa et al., 1977), the content of esterified polyhydroxy fatty acid may account for the range in bitterness of the various SPCs. However, whether soybeans contain free oxygenated fatty acids has not been determined. During maturation, bitterness in soybeans increases 3- to 4-fold, particularly in the latter stages of maturity. There is also a significant correlation between lipoxygenase activity and the formation of a bitter flavor (Rackis et al., 1979). 10 Cooked Soybean Odor Soy flour contains several phenolic compounds with ferulic, coumaric, syringic and vanillic acids being most prevalent (Maga, 1978). Phenolic acids may contribute bitter astringent flavors to soy flour (Arai et al., 1966). However, Rackis et al. (1967) stated that phenolic compounds had little significance in flavor of soy products. Nevertheless, when wet defatted soybean meal is sterilized or heated to high temperature (cooking, retorting), a very unpleasant cooked odor that many consumers find repulsive is generated. The cooked soybean odor is also characteristic of extruded soy flour and canned retorted TSPs (van den Ouweland and Schutte, 1978). This has been attributed to the formation of 4-vinylphenol and 4-vinylgUaiacol by the thermal decarboxylation of p-coumaric acid and ferulic acids, respectively (Greuell, 1974). 4-Vinylphenol has a strong smoky aroma and 4-vinyl- guaiacol tastes phenolic or bitter. These have flavor threshold of around 10-90 ppm (Maga, 1978) and contribute an unpleasant flavor to heated SPP. Sweet Taste A significant amount of sucrose (12%) present in defatted soy flour can influence the perceived flavor and, of course, on cooking can give rise to different flavors via the Maillard reaction. Pinitol, a sweet tasting alcohol has been found at a level of 0.3% in defatted soy flakes, and may also contribute to sweetness in TSPs (Honig, 1971). Burnt Flavor Under excessive heating and extrusion with high temperatures, a burnt flavor may be formed (van den Ouweland and Schutte, 1978). This 11 probably arises from the Maillard reaction between the amino acids and sugars (particularly the oligosaccharides) present in defatted soy flour. Qvist and von Sydow (1974) identified a host of compounds including aldehydes, ketones, furans, sulfur containing-compounds, and pyrazines in heated soy protein isolate. It is interesting to note that the concentration of almost all volatiles increases on heating, except for sulfur-containing compounds. All of these compounds could contribute burnt, cereal, nutty and toasted off-flavors to TSPs (Palkert, 1980). Alkyl-substituted pyrazines in deep fat-fried soybeans have been suggested to be responsible for their nutty aroma (WilkenS‘ and Lin, 1970). Contaminant Flavors Contaminant flavors may also form in SPPs, particularly in solvent- extracted preparations. Thus, off-flavors like sweet fusel notes or catty odors may arise from the formation of mesityl oxide from traces of acetone and hydrogen sulfide derived from sulfur-containing amino acids. These can be avoided by using purified solvents (van den Ouweland and Schutte, 1978). The myriad of volatile compounds (carbonyls, furans, alcohols, phenolic compounds, browning products and amines) found to be associated with SPPs are compiled and compared with cooked beef volatiles in a later section. Table 2 presents a condensed version of the significant research findings on the origin, nature, and control of off-flavors in SPP. 12 Table 2. Origin, nature, and control of off-flavors in soy protein productsa. Off-flavors Compounds Precursors Prevention/ responsible removal Green, Carbonyl compoundsb Polyunsaturated Heating intact grassy or fatty acids + beans, hexane beany lipoxygenase extraction Bitter Esterified poly- Phosphatidylcholines Alcohol hydroxy fatty acids, extraction fatty acid dimers, oxidized phospha- tidylcholine Cooked p-Vinylphenol, p-Coumaric acid, soybean p-vinylguaiacol ferulic acid (lignin) Sweet Sucrose, pinitol Burnt, Maillard reaction Amino acids + cerealy, products carbohydrates nutty, roasted Catty 4-methyl-4-mercapto- Acetone + hydrogen pentanone sulfide Fusel note Long chain alcohols Low heat treat- ment, alcohol extraction Water extraction Low heat treat- ment, water extraction Solvent removal Solvent removal aAdapted from Schutte and van den Ouweland (1979). bSee Table 1. 13 Flavor Binding in Songrotein Products The ability to mask undesirable flavors and simulate the desired meat flavor is significantly influenced by the flavor binding capacity of the protein used (Kinsella and Damodaran, 1980). Better under- standing of the binding and release of off-flavors from aqueous and dry soy systems is essential to the development of methods/processes to remove/minimize this flavor and increase the acceptability of SPPs in the marketplace (Kinsella and Damodaran, 1980; Aspelund and Wilson, 1983). In addition, this could aid in the retention of desired flavors in SPPs and could significantly improve the human consumption of SPPs (Schutte and van den Ouweland, 1979; Lyon, 1980). Soy Protein-flavor Interactions The problem of binding of flavors to proteins has received limited attention (Gremli, 1974; Beyerly and Solms, 1974; Franzen and Kinsella, 1974; Aspelund and Wilson, 1979, 1983; Damodaran and Kinsella, 1981a,b). Gremli (1974) was the first to systematically study the interaction of saturated and unsaturated aldehydes, phenolic alcohols, and phenolic and heterocyclic ketones with a 5% aqueous soy protein solution. Although all of the aldehydes and most of the ketones studied were bound to some extent by soy protein components, none of the alcohols examined were bound (Gremli, 1974). The percent retention of the aldehydes increased with increasing molecular weight and unsaturation. The ketones showed a different pattern of binding affinity. For the homologous series of 2-hexanone to 2-decanone binding to soy protein increased with moleCUlar weight, but ketones larger than 2-decanone, showed a reduced affinity for soy 14 protein. Phenolic ketones were bound by soy protein while low molecular weight ketones containing a furan ring were not bound. Among the compounds examined, only the aldehydes were retained irreversibly to some extent (25-51%). When measuring flavor retention by a 50% soy dough subjected to a high vacuum as a model for a mild drying process, all of the compounds tested including aldehydes, ketones, and even alcohols were strongly retained. However, when the dough was diluted to a 5% solution with water and then vacuum distilled, the ketones and alcohols were quantitatively removed, while the aldehydes were partially removed (Gremli, 1974). Gremli (1974) rightly points out that his data are not strictly applicable to TSP as TSP is only 50% protein and contains about 35% carbohydrates and 2% lipid which may bind flavor compounds. Secondly, the high temperatures and pressures involved in extrusion likely result in considerable losses of reversibly bound flavors. Thirdly, the denaturation and restructuring of proteins as well as other soy component interactions which occur during extrusion have an unknown effect upon soy protein-flavor interactions. Arai et al. (1970) quantitatively studied the interaction of hexanal and n-hexanol with native denatured and enzymatically hydrolyzed soy protein. The interaction of hexanal and n-hexanol increased with the degree of denaturation of soy protein and these flavors were not removed by vacuum distillation. The increased binding of these carbonyls by denatured soy protein, compared to native protein, was attributed to the greater exposure of hydrOphobic regions in the denatured protein. Arai et al. (1970) further showed that proteolysis of the denatured 15 protein decreased the amount of hexanal and n-hexanol retained by the protein. These results suggest that the interaction of flavor compounds with proteins is not via mere surface adsorption but through inter- action with specific hydrophobic regions in the protein. Using a gel filtration technique, Arai et al. (1970) obtained the binding constants, 173.4 M'1 and 80.3 M'l, for hexanal and n-hexanol respectively. These values suggest that the binding is relatively weak, and that the resistance to vacuum distillation cannot be interpreted in terms of strong interactions but possibly to entrapment of these compounds in the solid protein matrix. At saturation levels, the amounts of hexanal and n-hexanol bound to partially denatured soy protein was about 0.847 mg/g and 0.889 mg/g respectively (Arai et al., 1970). Assuming that the molecular weight of soy protein is 100,000, the total number of binding sites, calculated from the above values, in partially denatured soy protein is about one. For an oligomeric protein such as soy protein this value seems to be very low and cannot fully explain the inherent flavor problem in soy protein (Kinsella and Damodaran, 1980). In a different approach, Beyeler and Solms (1974) calculated the binding constants of a wide variety of flavor compounds to soy protein and bovine serum albumin (BSA) using equilibrium dialysis. They found that the binding constants decreased in the order: aldehydes, ketones, and alcohols. Carboxylic acids, dimethylpyrazine, aniline, and phenylalanine exhibited no affinity for soy protein. Vanillin and p—amino-benzoic acid, which contain more than one functional group, showed complex binding properties. These authors further demonstrated 16 that temperature (20-60°C) and pH (3.0-7.0) had little influence on the strength of binding. They believed this indicated that both ionic and hydrophobic forces were responsible for soy protein-flavor interactions, with hydrophobic forces being predominant. The binding constant for 2-butanone to a soy protein isolate at 20°C and pH 7.0 was estimated to be 5174 M'1 (Beyeler and Solm, 1974). This value seems to be very high when compared to that for hexanal obtained by Arai et al. (1970). This may be attributed to inadequate methods and inappropriate systems used by Beyeler and Solm (1974) (Kinsella and Damodaran, 1980). Beyeler and Solm (1974) surprisingly also found that BSA and soy protein showed very similar affinities for the same flavor compounds. They attributed this to the fact that both proteins have the same average hydrophobicity, and thus, infer that binding is primarily due to hydrophobic interactions. However, since the molecular structure of two different proteins can never be the same, the hydrophobicity of the binding sites and hence the magnitude of the hydrOphobic inter- action with the ligand varies (Kinsella and Damodaran, 1980). Therefore, it is unlikely that the binding constants for BSA and soy protein would be similar as reported (Beyeler and Solms, 1974). In 1974, Franzen and Kinsella studied the interaction of soy isolate and soy concentrate with C6-C8 aldehydes and ketones using headspace analysis. They found that all the flavor compounds except 2-heptanone interacted with the soy fractions, resulting in a decrease in their headspace concentration. In general, soy concentrate bound the flavor compounds more strongly than the soy isolate. They attributed 17 this to the higher carbohydrate and lipid content of the concentrate. More recently, Damodaran and Kinsella (1981a) studied the interaction of carbonyls (2-heptanone, 2-Octanone, 2- and 5-nonanone, and nonanal) with soy protein, using equilibrium dialysis. They found that at saturation level, soy protein exhibited four binding sites for all the carbonyls studied. The binding constant increased with the chain length of the ligand by 3 orders of magnitude for each methylene group increase in the chain. The favorable change in the hydrOphobic free energy was 550 cal/mol of CH2 residue. The position of the carbonyl group decreased the hydrOphobic free energy by 105 cal/mol for each shift from the terminal 1 position to the middle of the chain. The order of the binding affinity to soy protein is nonanal>2-nonanone>5— nonanone. This could be due to steric hindrance introduced by the presence of the carbonyl group as it is shifted to the center of the chain. While the binding affinity was independent of temperature above 25°C, a drastic increase in the binding affinity was Observed at 5°C. Partial denaturation of soy protein increased the binding constant. Thermodynamic analysis of the binding of carbonyls with soy protein revealed that the interaction is relatively weak. The effect of urea and succinylation of soy protein on the binding of 2-nonanone were studied by Damodaran and Kinsella (1981b). The addition of urea caused a decrease in the binding affinity of 2-nonanone for soy protein. The binding affinity decreased by about 50% in the presence of 1.5 M of urea. This is due to the interaction of urea with the hydrOphobic region of the soy protein resulting in the separation of subunits into their constituent polypeptide chains. Succinylation of 18 soy protein also resulted in conformational changes in the protein which destroys half of the four binding sites originally present for 2-nonanone. However, the intrinsic binding constants of 930 M’1 and 850 M"1 for the respective native and succinylated soy proteins are almost identical. The decrease in the binding constant in the presence of urea and succinylation was due to structural changes in the protein as evidenced by the changes in the fluorescence behavior of soy protein. Damodaran and Kinsella (1981b) also examined the binding affinities of 115 and 75 fractions of soy protein for 2-nonanone. While the binding affinity of the 7S fraction was the same as that of whole soy protein, the 113 fraction exhibited almost no affinity for 2-nonanone. These differences are interpreted in terms of the structural differences in these two proteins. Aspelund and Wilson (1983) reported the thermodynamic properties of the reversible adsorption of off-flavor compounds (homologous series of alcohols, aldehydes, ketones, hydrocarbons and methyl esters) onto soy protein isolate using gas chromatography and statistical linear analysis of triplicate samples ran at 80, 90, 100°C. The heat of adsorption of aldehydes, ketones, and methyl esters were not statistically significant from each other but were significantly different from the hydrocarbons and the alcohols. The hydrocarbons adsorbed the weakest and the alcohols adsorbed the strongest onto dry soy protein. Aspelund and Wilson (1983) concluded that the functional group of the ligand plays a significant role in binding of flavor compounds to soy protein in the dry state. 19 Palkert (1980) examined the TSP-flavor compound interactions with meat flavor system consisting of sulfides (C3-C4), disulfides (CZ'C4)’ heterocyclics (2,4-dimethylthiazole, 2,5-dimethylthiophene, furfural and pyrrole), and aldehyde (undecanal). The extent of TSP-flavor compound interactions was found to vary widely for different compounds. Using a Tenax trapping system for isolation of flavor compounds, recovery of the compounds in the presence of TSP ranged from 30% for undecanal to 88% for pyrrole when the model system was added at a level of 50 ppm. Increasing the concentration to 100 ppm increased the amount of flavor bound to TSP, indicating that additional binding was still occurring. The Tenax trapping system used was unsuitable for recovering compounds (2,5-dimethylfuran, 2,5-dimethylpyrazine, caprolactone, and octalactone) of high polarity and solubility in water. The former property slowed the migration of the compounds out of the aqueous phase while the latter acted to reduce the retention of the compounds by the Tenax column. TSP may interact with flavor compounds and lower their volatility in several ways. Franzen and Kinsella (1974) attributed the decrease in volatility of intermediate chain length aldehydes and ketones in the presence of TSP to a reduction in surface area and increase in solu- bility. Arai et al. (1970) believed hexanol and hexanal interacted with soy protein via hydrOphobic forces, while Beyeler and Solms (1974) indicated that both hydrophobic and ionic forces may bind flavor compounds to soy proteins. Much research effort is needed to examine the binding phenomena of desired meat flavor compounds (especially nitrogen-, oxygen- and/or 20 sulfur-containing heterocyclics, sulfides, and thiols) with SPPs, particularly, TSPs. Flavor Release in Sgerrotein Products van den Ouweland and Schutte (1978) studied the taste threshold values for some meat flavor components in four different media (Table 3). Table 3. Taste threshold values of meat flavor componentsa. Taste threshold value (ppm) in Compound water oil/water textured soy meat emulsion protein 2-Heptanone 0.08 1.00 1.00 5.00 1-0cten-3-ol 0.05 0.70 0.50 2.30 1,5-Dodecalactone 0.06 3.00 3.00 6.50 Benzaldehyde 0.05 0.40 0.60 2.00 2(H)-3-Furanone, 4-hydroxy-2,5-dimethyl- 0.03 0.20 0.10 5.70 aAdapted from van den Ouweland and Schutte (1978). For all the compounds tested, the threshold values are higher in the oil/water (O/W) emulsion than in water. The threshold values of the components in the O/W emulsion are of the same order of magnitude as those found for the TSP. In-bland-tasting freeze-dried meat pieces rehydrated with the same emulsion, the threshold values are in all cases higher than in the TSP. An explanation for this interesting phenomenon seems to be that during mastication of TSP, the flavors are expelled during the first bites, whereas in the meat system, the release is much more gradual (van den Ouweland and Schutte, 1978; Schutte and van den Ouweland, 21 1979). This is particularly true for water soluble flavor compounds, and unfortunately many meat volatiles and certainly the taste compounds are water soluble (Schutte and van den Ouweland, 1979). The practical solution for the release of flavor constituents as proposed by Schutte and van den Ouweland (1979) are: (a) developing meat flavor blends adaptable to the quick release of water from material, (b) restricting TSP to small particle size to avoid prolonged chewing, and (c) intensive blending with other ingredients in the food, for example, comminuting or mincing together with meat. Chemistry of Meat Flavor: An Overview Flavors for meat extenders or analogs must be far superior to the traditional blend of flavors used for imparting meat flavors to soups and gravies (Kuramoto and Katz, 1975). When the addition of TSPs in comminuted meats exceeds 20%, the flavor generated by the meat cannot mask the natural, undesirable flavors of the extender. Thus, there is a real demand for meat flavor precursor systems whose potency is thermally generated. A complete appreciation of all meat aroma chemicals and the apprOpriate use of precursors is the only way to ensure a wide range of processed and novel foods which will be attrac- tive to the consumer (Schutte, 1976). Hence, a brief overview Of the chemistry of meat flavor is presented. The scape of the background literatures in the fields of natural and simulated meat flavor is vast. Review articles worthy of particular note are those by Herz and Chang (1970), Dwivedi (1975), MacLeod and Seyyedain-Ardebili (1981), and Shahidi et al. (1986). 22 Meat composes a wide variety of foods originating largely from beef, pork, lamb, and chicken. Flavor is one of the most important quality attributes which contributes to the acceptability of meat. Raw meat has little odor and only a metallic, blood-like taste, whereas cooking develops its flavor (Crocker, 1948). A meaty flavor is believed to originate from the lean portion of meat and a species flavor from fat (Hornstein and Crowe, 1960; Allen and Foegeding, 1981). It has been suggested that the meaty flavor derived by heating the water-soluble precursors in the lean portion is the same regardless of the type Of meat from which the precursors are Obtained (Hornstein and Crowe, 1960). The early work on meat flavor which began during the 19505 was almost exclusively concerned with the identification of the water- soluble, non-volatile precursors of meat flavor and was reviewed by MacLeod and Seyyedain-Ardebili (1981). Hornstein and Teranishi (1967) summarized the early work on meat flavor precursors as follows: (1) Only low molecular weight water-soluble materials are meat flavor precursors; ' (2) The high molecular weight proteins (muscle fibrils and sarco- plasmic proteins) do not contribute to the formation of meat flavor; (3) The free amino acids and carbohydrate components Of lean pork, beef, and lamb are similar, and this is reflected in the similarity of their lean meat flavor; (4) A specific glycoprotein and inosinic acid may be precursors of beef flavor or parts thereof; and, (5) Browning-type reactions may not be the sole mechanism responsible for the production of lean meat flavor. According to Dwivedi (1975) the flavor of cooked meat is due to a mixture of compounds which include: (a) non-volatile, water soluble 23 compounds with taste and tactile properties, (b) potentiators and synergists such as L-amino acids containing five carbon atoms and/or 5'-nucleotides, and (c) volatile components with odor properties. Of these, the volatile or aroma compounds are by far the most important. Their formation and relative contribution to cooked meat aroma will be discussed. Maillard Reaction Products and Meat Aroma The main types of heat-induced reactions leading to the formation of meat flavor volatiles from non-volatile precursors have been summarized by van den Ouweland et al. (1978) as follows: (1) Pyrolysis Of peptides and amino acids, (2) Degradation of sugars (particularly reducing sugars), (3) Interactions involving sugars, peptides, amino acids, or their degradation products (Maillard reaction), (4) Degradation and reaction of ribonucleotides, (5) Reaction of hydrogen sulfide, ammonia, and thiols, with volatile and non—volatile components, (6) Oxidation, hydrolysis, dehydration, and decarboxylation of lipids, and, (7) Thiamin degradation. Because of its importance in flavor propagation, the Maillard reaction has recently been reviewed by many workers including Tressl et al. (1979), Tressl (1979), Baltes (1980), Nursten (1980), and Danehy (1986). Only those aspects of the reaction which are best understood and are likely to be important in their contribution to meat aroma will be discussed. 24 The Maillard or non-enzymic browning reaction is induced by heating a free amino group (amino acids, amines, peptides, proteins, ammonia) with carbonyl compounds (aldehydes, ketones, reducing sugars) (MacLeod and Seyyedain-Ardebili, 1981). It is an open ended complex reaction consisting of a series of interactions and decompositions and resulting in numerous products frequently including mono- and dicarbonyls, furans and derivatives, alcohols, cyclic ethers, and heterocyclics. Factors Affecting_the Maillard Reaction The reaction can occur at 90°C, is inhibited by water, and increases with time and temperature (Wang and Odell, 1973). Chuyen et al. (1973) have reported that peptides are more reactive than amino acids in non- enzymic browning. The effect of water content of the food is important (van den Ouweland et al., 1978). For example, Optimal formation of Amadori products (APs) from glucose/amino acid occurs at a water content of 25 to 30% (model system 100°C/1 hr)(van den Ouweland et al., 1978), a region often encountered during cooking and processing. van den Ouweland et al. (1978) reported that during frying of meat, approximately 60% of the water is lost. In the surface layers, this loss is even higher, and conditions are created at which the Maillard reaction is favored (van den Ouweland et al., 1978). A considerable decrease in amino nitrogen and in glucose, fructose, and ribose concentrations occurred when a beef diffusate was heated (125°C/1 hr; Wasserman and Spinelli, 1970) and the glucose/glycine APs have been isolated from roasted meat (van den Ouweland et al., 1978). Nursten (1980) summarized the important factors such as temperature and time of reaction, proportion and nature of reactants, and water 25 activity. The effect of temperature on browning is marked, 010 values being 3-6. There are some clear effects on the nature of the reactants: pentoses react more quickly than hexoses; thiazoles are specific to cysteine, and pyrroles to pyrroline. As regard to proportion of reactants, there is a general tendency for model systems not to be moved away from a 1:1 ratio of sugarzamino acid. Reaction Mechanisms In order to understand the wealth of compounds generated, the current mechanistic proposals will therefore be briefly reviewed. The Maillard reaction is best divided into three stages (Hodge, 1953, 1967; Mills et al., 1969) and the overall reaction scheme is outlined in Figure 2 (Hodge, 1967). N-Subsiiiuiod glycosylamine ——*529—- Aldohexoso + Amine / / S-H dno ethyl- HC-N = y xym II \ H? N\ ”920 HT=O -H20 2-iuraldahyde 9-0” 0H9 (II-0H 0 (i=0 H 0 (3:0 (EHOH—u- (';H 1112—. 9H2 :_2_. |C|H CHOH CHOH CHOH CH ‘0' N". '0 + Amlh e c-N” I I I I +fi0 H2. \\ I I I 930 1 .z-Eneaninol . 3-Deoxyhexosone THO” n we MelanoIdins (EHOH ' fl... Amadori \ H2?- CH2 OH, CIZHa +120 " +Amhe \ ll “ Amne ' ' I I H H CHOH SSHOH CHOH C O \ C—methyireduaones l | I anda—dcabonyls 2.3-Enodol Mew [PynNaIdehyde. aceiol. aacmumw waxWLmanMammfl Figure 2. Sugar-amine (Maillard) browning reactions: Two pathways to melanoidins and by-products (Hodge, 1967). 26 The first stage comprises glycosylamine formation and subsequent rearrangement. This involves an addition reaction of the amine to the carbonyl group, followed by elimination of water to form a Schiff base. The Schiff base cyclizes producing an N-substituted glycosylamine, which undergoes an acid-catalyzed Amadori rearrangement forming the Amadori product N-substituted-l-amino-I-deoxy-Z-ketose. The intermediate stage comprises dehydration, either by loss of three molecules Of water to furfurals or by loss of two to reductones, fission (mainly by dealdolization), and Strecker degradation (the interaction of amino acids and dicarbonyl compounds which may either be dehydroreductones or dehydration/fission products). The final stage consists of the conversion of carbonyl compounds (dehydroreductones, dehydration/fission products, or Strecker alde- hydes) into high molecular weight products, the melanoidins, with further involvement of amines where these are available. Its Role in Meat Aroma Production The aroma volatiles produced by the Maillard reaction are best classified into three groups (Nursten, 1980): (1) "Simple" sugar dehydration/fragmentation products (furans, PYPOOES. Cyclopentenes, carbonyls, acids); (2) "Simple" amino acid degradation products (aldehydes, sulfur compounds); and, (3) Volatiles produced by further interactions (pyrroles, pyridines, imidazoles, pyrazines, oxazoles, thiazoles, compounds from aldol condensations). The formation of some of these compounds, especially the latter ones which may be significant contributors to meat aroma (see following section), are herein reviewed. To aid in subsequent 27 discussions, the parent structures of some of the heterocyclics are presented in Figure 3. 5? <9 (9.} A??? 4?} 49"» <9 Pynoie Fman Thiophene Imidazole Oxazole Thiazole Pyrazole 3 Pyrmline Pyrrolidine Pyridine Pyrimidine Ouinoiine IsquinoIine Figure 3. Parent structures of some heterocyclics (Morrison and Boyd, 1976). The non-volatile APs are the key compounds in that they are heat- labile and, on low temperature thermolysis, decompose forming volatile flavor compounds via 1-deoxysones and 3-deoxyosones, respectively (Tressl et al., 1977). The former may be transformed into decarbonyls with which amino acids can undergo Strecker degradation. The amino ketones simultaneously formed may be transformed into pyrazines. For example, R‘ R R‘ N R \c=o HzN—cfiH / H—C'B-NH + o-c': -H O \ I substituted pyrazine Some simple reactions of APs are presented in Figure 4 (Hodge, 1953; Tressl et al., 1977). (a) (b) (C) (d) Figure 4. R-III—H afi - (I'm -3H20 (”’94)"): CHon AP from a pentose + RNHz R-P'J-H ‘sz C=O I (Ike-OH). CH20H AP from a hexose + RNHQ -3H20 R-r'J-H 9“: $30 fl— deabolzation 0* ? (”0" &flsbnd CH,OH carbohydrate AP R-r'J—H THZ oxidation =0 l (H-c-OH) ,, CHZOH AP 28 E1 u 9” H + (xx 9:0 SI I H-(‘z-NHZ aldehyde (H-C-OH)".1 (HfiOH Tressl et al., 1977). a-aminoaceione Some simple reactions of Amadori products (Hodge, 1967; 29 Further reactions of the unstable APs on heating have been reported (Tressl et al., 1979; Mills et al., 1969; 1970; Mills and Hodge, 1976). The reaction conditions and the character of the amino compound deter- mine the range of aroma components formed (Tressl et al., 1979). A. Furan and Derivatives. A scheme for the formation of several furan derivatives identified in beef aroma has been presented by Tressl et al. (1979) and is summarized as Figure 5. While hexoses form 5-methylfurfural and 4-hydroxy-2,5-dimethyl-3(2H)- furanone, pentoses give rise to furfural and 4-hydroxy-5-methyl-3(2H)- furanone, respectively. This latter compound has been synthesized by heating amines with xylose, ribose, ribose-S-phosphate or incidentally, glucuronic acid (Hicks and Feather, 1975; Hicks et al., 1974). During these reactions, the oxygen of the furan ring may be substituted by nitrogen or sulfur, forming the corresponding pyrroles and thiOphene derivatives (Tressl et al., 1979). Shibamoto et al. (1977) identified several pyrroles in the reaction mixture of furfural, ammonia, and hydrogen sulfide showing that exchange of nitrogen for the oxygen in the furan ring does occur on heating. . B. Maltol. Maltol, in beef aroma, may arise from decomposition of a hexose AP. Its immediate precursor is probably 5-hydroxy-5,6- dihydromaltol, an important precursor of caramel compounds (Tressl et al., 1979) and identified in sugar-amine model reactions by Mills et al. (1970). This compound, together with smaller amounts of cyclo- tene, 2,5-dimethyl-2,4-dihydroxy-3(2H)-furanone and S-hydroxymaltol, were formed on decomposition at 140°C of 1-deoxy-1-L-prolino-D-fructose as shown by Mills and Hodge (1976) in Figure 6. 30 H\ 40 - II II ——> II II I ““20 H°H2C argon (3:0 5-hydroxymethyI-o 2 5-dihydroxy- Ii“ furfural methylfuran CH \ £10,0—» 11 CHZOH CH,0H 3-deoxyhexosone 5-methylfurfuralo 2-h)rfermfznr::y'-5. ~20 9“ Hzc—NHR i=0 Ho-C—H H-(iZ-OH H-D-OH CHZOH glucose AP “’4’ ’2; 9”: II II $=0 / o COCH, c=o 2—acetylfuran I H-C-OH \ ' HO H-c-oH I CHZOH o 1 -deoxyhexosone 4-hydroxy-2,5- dimethyl-3(2H)- furanone Formation of furan derivatives from glucose Amadori products (Tressl et al., 1979). 31 AMADORI COMPOUND 9.9. (1 -deoxy-1-L-prolino-D-fmctose) C) C) 0 0H 0 OH HO OH Ho OH U + I.:UE + I + I I HO 0 CH, 0 CH, cyclote ne 2,5—dimethyI-2,4- 5-hydroxy-5,6- 5—hydroxy- 4 dihydroxy-3(2H)- dihydromaltol maltol furanone A proline V C) C) 0 OH OH Ho OH + I II ” | l I I H30 0 CH3 0 CH, 0 CH, 4-hydroxy-2,5- maltol 5-hydroxymaltoi dimethyI-3(2H)- furanone Figure 6. Formation of maltol and derivatives from Maillard reaction (Mills and Hodge, 1976). 32 On heating with proline, 5-hydroxy-5,6-dihydromaltol give rise to 5-hydroxymaltol, maltol and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Mills and Hodge, 1976). The latter two have been identified in cooked beef aroma. Proline and hydroxyproline have secondary amino groups and therefore do not undergo Strecker degradation. C. Pyrroles, Pyridines. The formation of several pyrroles (pyrrole, 2— and 3—methyl-, 2-ethyl-, 2,5-dimethyl, N-methyl-, and N-propyl-pyrrole) and pyridines (pyridine, 2- and 3-methyl-, 2-ethyl-, 2,3-dimethyl-, and 2-formyl-pyridine) from the reaction of proline and glucose under roasting conditions has been reported (Tressl et al., 1979; Shigematsu et al., 1975). Several N-acyl-pyrrolidines and 2,3-dihydroindolines were also reported, but have not been identified in beef aroma. Bicyclic pyrrole compounds have also been isolated from a proline/glucose model reaction (Shigematsu et al., 1975). The similar reaction of hydroxyproline with glucose has produced over 50 nitrogen heterocycles and in contrast to the proline system, only N-substituted products were obtained (N-alkylpyrroles, N-acylpyrroles, and N-furfuryl- pyrroles). The 2,3-dihydroindolenes were again identified, but no pyridines. Tressl et al. (1981) characterized 5,6,7,8-tetrahydro- indolizin-6-ones, 1-furfuryl-pyrroles, 1-(pyrrolyl)-2-butanones, 1-(pyrrolyl)-3-buten-2-one, 2— and 5-(1-pyrrolyl)cyclopentenones and 2-[(1—pyrrolyl)methle-cyclopentenones as specific compounds derived from hydroxyproline/glucose or arabinose (erythrose) model experiments. None of these compounds have been identified in cooked beef aroma. D. Pyrazines. The pyrazines most frequently produced thermally are the alkyl, alkenyl, and acyl pyrazines. Mechanisms of their formation 33 have been reported (Rizzi, 1969; 1972; Shibamoto and Bernhard, 1977; Dawes and Edwards, 1966). They can be formed as already described by dimerization of a-aminoketone Strecker products. Newell et al. (1967) using a model system of glucose/amino acid, and van Praag et al. (1968) using glucose/ammonia, both concluded that the reaction required free ammonia and that the same pyrazines were produced regardless of the amino acids since it only served as a source of free ammonia (Wasserman, 1979). Conversely, Koehler and coworkers (Koehler et al., 1969); Koehler and Odell, 1970) showed that the amino acid nitrogen reacts directly with the sugar system producing different pyrazines. The type and concentration of pyrazines formed depended on the carbon source (the particular sugar or sugar degradation products: glyoxal, acetaldehyde, glycerol, propanal, hydroxyacetone, and butane-2,3-dione, and also glucosamine). Shibamoto and Bernhard (1976; 1978) using sugar/ammonium hydroxide model systems, showed that glucose gave a series of alkylpyrazines, while rhamnose produced a series of dihydrocyclopentapyrazines and tetrahydroquinoxalines. Both of these classes of compounds have been identified in cooked beef aroma. Shibamoto and Russell (1976; 1977) heated a solution of glucose, ammonia, and hydrogen sulfide. The volatiles produced resembled Closely beef odor and included thiophenes, furans, 2,4-dimethyl-3- thiazoline, methanethiol, dimethylsulfide, alkylthiazoles, and pyrazines; several of the compounds formed have been identified in cooked beef aroma. Increasing the concentration of ammonia increased the total yield of pyrazines and also changed the ratio of the individual pyrazines formed, due partly to a greater amount of ammonia available 34 for reaction and partly to increased pH causing greater fragmentation of the sugar and the formation of more carbonyl compounds (Shibamoto et al., 1977; Shibamoto and Bernhard, 1976; Shibamoto and Russell, 1976; 1977). Wasserman (1979) explains that when meat is initially heated (normal pH 5.5 approximately) the mechanism for pyrazine formation, involving carbonyl-amino acid (or amine) reaction, is likely to be favored but as the concentration of ammonia increases on libera- tion from amino acids on continued heating, the pH increases and induces the reaction described above by Shibamoto and his CO-workers. Using the same model system, Shibamoto and Russell (1976) determined the effects of temperature on pyrazine formation. Although some pyrazines were formed at -5°C (after 30 days) significant pyrazine formation began at 70°C and increased to Optimum at 120°C/2 hr (Shibamoto and Bernhard, 1978; Shibamoto and Russell, 1976). Reineccius et al. (1972) also showed that pyrazine formation occurred at time-temperature relationships as low as 30 min at 70°C. Other investigators have reported no pyrazine formation below 100°C (Wasserman, 1979). They were formed in greater concentrations during cooking of beef by microwave radiation than by conventional means (MacLeod and Coppock, 1976). Alkyl-SH-6,7-dihydrocyclopenta-[OI-pyrazines, present in both boiled and roasted aromas of heated beef, arise from condensation of hydroxycyclopentenones with a-dicarbonyls in the presence of ammonia (Flament et al., 1976a,b). All these reactants are available in heated meat. Alkyl hydroxycyclopentenones are Maillard reaction products; a typical example is 2-hydroxy-3-methylcyclopent-Z-enone (cyclotene). The series of reactions leading to the formation of the pyrazines is 35 shown in Figure 7. Pyrrolo 1,2-a pyrazines probably arise by condensation of a sugar degradation product (a-dicarbonyl compound) with a Strecker degradation product (a-aminocarbonyl compound) in the presence of ammonia (Flament et al., 1977) as illustrated in Figure 8. van den Ouweland et al. (1978) concluded that the majority of the volatile products evolved from heating the APs of glycine/glucose and of glycine/fructose above their melting points were furan and pyrrole derivatives. E. Thiophenes. Maillard reactions involving cysteine and/or cystine have been extensively studied (Arroyo and Lillard, 1970; Kato et al., 1973; Scanlan et al., 1973; Mulders, 1973; Kleipool and Tas, 1973, 1974; Ledl and Severin, 1973; 1974). Possible reaction products are carbonyl compounds, amines, benzenoids, acids, lactones, thiols, furan derivatives, thiOphene derivatives, thianes, thiolanes, pyrroles, pyridines, pyrazines, thiazoles, thiazolines, and thiazolidines. Kato et al. (1973) showed that far more thiOphene derivatives arise from cysteine/pyruvaldehyde reaction than from the corresponding reaction involving cystine. They made similar comparisons of glucose/cysteine and glucose/cystine reaction products and showed that more thiophenes and pyrazines were identified in the cysteine system while more thiazoles and furan derivatives arose from cystine. Thiophene deriva- tives have also been eminent in the reaction products of cysteine/ xylose, a model system approximating cooked meat (Mussinan and Katz, 1973), and in a cysteine/cystine-ribose system. Mulders (1973) proposed a scheme for the formation of 5-methylthiophen-Z-carboxaldehyde from 36 (a) 0 NH NH2 I + NH3 ——-> [H] I I -H20 0 o o a-diketone (butan-2,3-dione) N” -H20 2X 'H20 0 II I"): TY \N 0H HN IO\ /H20 :ENE \N tetrarnethylpyrazine (b) O O HN N I + NH3 4» 103° I + I I O HO 4h HO \N cyclotene 54mino-2— methylcyclopent- 2-en-1-oi \L Isl ‘V’77 II]? 5:55 DESI? + U213- 2.3,5-trimethyI-5H-6,7- dihydrocyclopenta [b]- pyrazine Figure 7. Formation of alkyl-5H-6,7-dihydroxycyclOpentaLb]-pyrazines from Maillard reaction products (Flament et al., 1976). 37 (an-dicarbonyl hexose pentose ——> CHZOH CHZOHI Fl R amino acid SD NH2 -H20 0 + R3’/L\I“c> '7 R3 ’JD OI-dicarbonyl R2 -H20 compound a—aminocarbonyl compound 4 NH3 N I R‘ (D C) R2 -H20 I l ,1 N I Rz pyrrolo [1.2-3] pyrazine Figure 8. Formation of pyrrolo [1,2-a] pyrazines (Flament et al., 1977). 38 reaction of mercaptoacetaldehyde and but-2-enal which can arise from aldol condensation of acetaldehyde followed by dehydration. As far as foods are concerned, with the exception of American cranberries (Anjou and von Sydow, 1967), thiOphenes and their derivatives have been identified exclusively in cooked or roasted foods (Ohloff and Flament, 1978), and so their formation from Maillard type reactions involving cysteine seems very likely. Interaction of glucose degradation products with hydrogen sulfide also produces thiophenes, including thiOphene aldehydes and ketones (Shibamoto and Russell, 1976; 1977). Tetrahydro- thiophen-2-one, tetrahydrothiophen-3-one and its methyl homolog have been identified in model reactions of cysteine with xylose (Mussinan and Katz, 1973), glucose (Scanlan et al., 1973), or pyruvaldehyde (Kato et al., 1973L Several mercaptothiophenes result from the reaction of hydrogen sulfide with 4-hydroxy-5-methyl-3(2H)-furannone or its 2,5-dimethyl homolog (van den Ouweland and Peer, 1975), but none of these have been identified in cooked beef aroma. Neither have thienothiophenes, known to arise from cysteine/cystine-ribose (Mulders, 1973) and cysteine/glucose (Scanlan et al., 1973; van den Ouweland and Peer, 1975) reactions. Recently, Shu et al. (1986) identified twenty- four volatile components including two novel compounds, 3-methyl-2- (2-oxopropyl)- and 2-methyl-3-pr0pionylthiophene from the reaction of cysteine and 2,5-dimethyl-4-hydroxy-3(2H)-furanone. F. Thiazoles. Alkylthiazoles and acylthiazoles have been isolated from model reactions of cysteine/cystine with xylose (Ledl and Severin, 1973), ribose (Mulders, 1973), pyruvaldehyde (Kato et al., 1973) or glucose (Kato et al., 1973). Alkenyl thiazoles were also identified in 39 the cysteine/xylose reaction (Ledl and Severin, 1973). 2,4-Dimethyl-5- vinylthiazole is easily formed by dehydration of the corresponding alcohol, 5-(2-hydroxymethyl)2-4-dimethylthiazole (Stoll et al., 1967). The acetylthiazole may arise from oxidation of 2-acetylthiazoline believed to arise from Strecker degradation of cysteine by pyruvaldehyde (Mulders, 1973) or from the addition of pyruvaldehyde to cysteamine and subsequent oxidation (Ohloff and Flament, 1978). Several 2-alkyl-thia- zolines and 2-alkylthiazolidines have also been identified in cysteine/ sugar reactions (Kato et al., 1973; Ledl and Severin, 1972), but have not been reported in beef aroma. G. Oxazoles,,0xazolines. Oxazoles may arise by Strecker degrada- tion of aminoketones resulting from the condensation of a-dicarbonyl compounds with amino acids (Ohloff and Flament, 1978). The model reaction of furfural, hydrogen sulfide, and ammonia produces 2,4- dimethyloxazole (Shibamoto et al., 1977). 2,4,5-Trimethyl-3-Oxazoline is formed from reaction of alanine and butane-2,3-dione (Rizzi, 1969) and from the reaction of two carbonyl compounds (acetaldehyde and acetoin), in the presence of ammonia (Jassmann and Schulz, 1963). H. S-containing Compounds. Several of the sulfur compounds identified in cooked beef aroma may arise from the Maillard reactions or Strecker degradation of cysteine and cystine. Hydrogen sulfide is a common heat-induced product, formed from interaction of cysteine with xylose (Ledl and Severin, 1974), ribose (Mulders, 1973) or a-diketones (Kobayashi and Fujimaki, 1965) and also on pyrolysis of sulfur- containing amino acids. Methanethiol is mainly formed by cleavage of ' methionine (Wainwright et al., 1972; Fujimaki et al., 1969). Short 40 chain aliphatic thiols are formed in cysteine/cystine-ribose reactions (Mulders, 1973). Benzylmethylsulfide has been isolated in a cysteine/ xylose model system approximating cooked meat (Mussinan and Katz, 1973), although it has not been identified in beef aroma. The diastereoisomeric, 3,5-dimethyl-1,2,4-trithiolanes, thialdine, aliphatic disulfides and dimethyltrisulfide have also been identified in the cysteine/xylose model reaction (Mussinan and Katz, 1973). Apart from contributing to meat flavor, hydrogen sulfide also acts as a precursor for other flavor compounds (van den Ouweland and Peer, 1975, 1978; Takken et al., 1976). It is evolved continuously on simmering beef; its release increases with time and coOking temperature, probably as a result of protein denaturation and reduction of disulfide linkages to thiol groups (Wasserman, 1979). Persson and von Sydow (1973) showed that as cooking time of canned beef increased from 15 to 75 min, hydrogen sulfide evolution increased 3-fold. Methanethiol and ethanethiol also increased in concentration in the aroma volatiles. On storage of the product, however, marked losses of both hydrogen sulfide and methanthiol occurred (Persson and von Sydow, 1974), possibly due to interactions with other components in the beef (Wasserman, 1979). Beef Flavor Volatiles To date, about 700 volatile compounds from various heated beef samples have been identified (Ching, 1979; Uralets and Golovnja, 1980; Yamaguchi et al., 1980; Lee et al., 1981; MacLeod and Seyyedain-Ardebili, 1981; Shahidi et al., 1986). These and some of their odor descriptions are listed together with the soy protein volatiles in Table 4. 41 Table 4. Chemical compounds and Odor descriptions of beef and soy flavor volatiles. Chemical compound Beef Soy Odor descriptions ‘ volatile volatile (References)a HYDROCARBONS Aiphatic, acyclic Methane, diisoproproxy 91a Methane, methyldithia 85 Butane 1 Butane, 2-methyl 2 Butane, dimethyl 3 Pleasant, sweet (3) Pentane 1,70 84 Pentane, 2-methyl 4,5 Pentane, 3-methyl 5 Pentane, 1,5-diamino 8O 1-Pentene, 2-methyl 6 2-Pentene, 4—methyl 5 1,4-Pentadiene 84 Hexane 1,5-8,7O Hexane, 2-methyl 5 Hexane, 3-methyl 5 Hexane, 2-methyl-3- ethyl 5,6 1—Hexene 3 Dull, cardboard (3) 2-Hexene 6 2,4-Hexadiene 6 Heptane 1,3-6,9,7O Cooked meat (3) Heptane, 2-methyl 3 Solvent-like (3) 1-Heptene 3,6,9 Sulfurous (3) 2-Heptene 6 Octane (and isomers) 1,3-6,9,10 92 Meaty (3) Octane, 2-methyl 4,5 Octane, 3-methyl 5 Octane, 2,6-dimethyl 5 1-Octene 3,6,10 3-Octene 6 1,3-Octadiene 11 92 2,4,6-Octatriene, 2,6-dimethyl 5 Nonane 3,6,10,13 Strong, sour, harsh, burnt, unpleasant (3) Nonane, 3-methyl 5 Nonane, 4-methyl 5 1-Nonene 3,6 Strong, grassy, onion, rancid (3) 3-Nonyne 12 Table 4 (cont'd.) 42 Chemical compound Beef Soy Odor descriptions volatile volatile (References)a Decane 3,9,10,13 84 Decane, 3-methyl 84 1-Decene 3 Strong, cardboard (3) 2-Decene 6 Decyne 11 Undecane 3,6,10,13 Undecane, 3-methyl 5 1-Undecene 3,7 Unpleasant, old meat 3 4-Undecene 3,9 Dodecane 1,4-7,10,13 92 Dodecane, 2-methyl 4,5 1-Dodecene 3,5,6 Medicinal (3) Tridecane 4-6,8,10,13,7O Tridecane, 2-methyl 4,5 Tridecane, 3-methyl 5 Tridecane, 4-methyl 5 1-Tridecene 3-5 Tetradecane 4-6,9,13 Tetradecane, 2-methyl 6,11,13 Tetradecane, 6-methyl 13 Tetradecane, 4-ethyl 5 1-Tetradecene 5 Pentadecane (and 4-9,13 isomers) Pentadecane, 2-methyl 4,5 Pentadecane, 3-methyl 11 1-Pentadecene 5,7,8 1-Pentadecene, 2-methyl 5 Hexadecane (and 4,6-9,13 isomers) Hexadecane, 2,6,10,14- 5,14 tetramethyl (phytane) 1-Hexadecene 5 Heptadecane 4-6,8-10,13 92 1-Heptadecene 4-6,13 Octadecane 4-8,13 Octadecene 15 Nonadecane 15,16 92 Eicosane 17 Henicosane 15,16 Docosane 15,16 Tricosane 15,16 Tetracosane 15,16 Table 4 (cont'd.) 43 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pentacosane 15,16 AllO-ocimene 5 Aliphatic, cyclic Cyclopentane, methyl 5 Cyclohexane 4,5,18 Cyclohexane, methyl 4,5 Cyclohexane, trimethyl 5 Cyclohexane, ethyl 4,5 Cyclohex-l-ene, ethyl 84 a-Pinene 92 B-Pinene 92 Limonene 5,6 92 a-Terpinene 5 92 B-Terpinene 92 y-Terpinene 92 Terpinolene 92 4-Terpineol 92 e-Caryophyllene 4,5 p-Cymene 92 a-Phellandrene 5 B-Phellandrene 92 Aromatics Benzene 4,7-9,19-21 84,91,92 Benzene, alkyl 10 (MW 134) Benzene, methyl 3-7,9,10,13, 91,92,93 Strong, fruity, 21,22,70 becomin dank, bitter I3) Benzene, 1,2- 9,10,13,21 91,92 Sweet (3) dimethyl Benzene, 1,3- 4,5,13 91,92 dimethyl Benzene, 1,4- 6,9,10,13,21 91,92 Fruity, solvent-like, dimethyl sickly, fatty (3) Benzene, trimethyl 13 (3 isomers) Benzene, 1,2,3- 10,21,23 trimethyl Benzene, 1,2,4- 6,10,21,23 trimethyl Benzene, 1,2,5- 5 trimethyl Benzene, 1,3,4- 23 trimethyl Table 4 (cont'd.) 44 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Benzene, 1,3,5- 6,10,21 trimethyl Benzene, 1,2,3,4- 6 tetramethyl Benzene, 1,2,3,5- 6 tetramethyl Benzene, ethyl 5,6,10 91,92 Benzene, methylethyl 6,23 Benzene, ethyl-2- 5,6,10,21,23 methyl Benzene, ethyl-3- 4,5,21,23,24 methyl Benzene, ethyl-4- 21 methyl Benzene, diethyl 5,13 Benzene, 1,2-diethyl 5 Benzene, vinyl 3,5,6,10 91 (styrene) Benzene, vinyl 10 methyl Benzene, vinyl 5,6 dimethyl Benzene, propyl 84 Benzene, propyl- 5-10 dimethyl Benzene, methyl-2- 23 prOpyl Benzene, methyl-3- 23 propyl Benzene, methyl-4- 5,6,18 isopropyl Benzene, 2,4- 11 dimethyl-1- isopropyl Benzene, ethyl-2- 23 propyl Benzene, ethyl-3- 23 prOpyl Benzene, butyl 6,13 84 Benzene, pentyl 6,13 Benzene, hexyl 6 Benzene, heptyl 6 Benzene, octyl 6 Benzene, decyl 5 Indane 3 45 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions volatile volatile (References) Indene 23 Naphthalene 4-6,10 91,92 Naphthalene, 2-methyl 5,10 Phenanthrene, 9,10- 91 dihydro-Z-N-dodecyl Subtotal (%) 122 (17.5%) 34 (13.5) ALDEHYDE Aliphatic Methanal (formalde- 2,25,26 78 hyde) Ethanal (acetalde- 2,21,25—32,7O 78,82,84, Pungent (21) hyde) 87,89,90 Ethanal, phenyl 5,10,22 85,86,90,93 Propanal 2,8,25,26, 9O 29-32,7O Propanal, 2-methyl 2,9,21,26,29, 84,95,90,92 Green, pungent, sweet 31,33,70 (21) Propanal, oxo 34 Propenal (acrolein) 34 87 Propenal, 2-methyl 9O Butanal 4,5,18,21, 84,90,91 Burnt, green, nasty- 23,26 smelling (21) Butanal, 2-methyl 2,9,6,13,21, 90,92 Burnt, sickly (21) 26,29-31,70 Butanal, 3-methyl 3-5,7,8,13, 90,92 Burnt, roasted (4), 21,26, meaty, sulfurous (3) 29-31,39,7O buznts green, sickly 21 Butanal, 2-ethyl 4,5 Butenal (crotonalde- 26,34,70 hyde) 2-Butenal, 2-methyl 90 Pentanal 6-8,13,19- 84,90-93 Burnt, green (21) 21,26 Pentanal, 2-methyl 26 Pentanal, 3-methyl 26 Pentanal, 3-methyl- 5 4-oxo 2-Pentenal 26 84 2-Pentenal, 2-methyl 90,91 4-Pentenal 26 Hexanal 3-8,10,13, 78,82,84,85, Strong, rancid, 19-21,25,32,70 89,90-92, unpleasant (3), 93 green, pungent, sickly (21) Hexanal, methyl 9O Table 4 (cont'd.) 46 Chemical compound Beef Soy Odor descriptions volatile volatile (References) 2-Hexenal 5,6,13,32 84 2,4-Hexadienal 6,26 84,90 Heptanal 4-8,10,13, 84,90-93 Green, burnt, sickly 19-21,26,35 (21) Heptanal, 2-methyl 5 2-Heptenal 5,6,13,26,32 78,82,84,89,93 4-Heptenal (cis) 36 Green, tallowy, creamy, butterscotch- like (36) 4-Heptenal (trans) 36 Green, tallowy, creamy, butterscotch- like (36) 2—Heptenal, 5-methyl 34 2-Heptenal, 6-methyl 7,8,34 2,4-Heptadienal 5-7,10,32,71 84,90 Octanal 5,7,8,10, 84,90-93 13,19,26 2-Octenal 5,7,8,13, 84 26,32 2,4-Octadienal 13 Nonanal 4,5,7,8,10, 84,90,92 Green, moldy (21) 13,19-21,32, 70,72 2-Nonenal 5,13,32 84 2,4-Nonadienal 5,13 84,91 Pleaiant, fried fat 5 2,6-Nonadienal 36 Green-cucumber-like (trans, cis) (36) 2,6-Nonadienal (trans, 36 Green-cucumber-like trans) (36) Decanal 5,10,13,26,37 90,92,93 2-Decenal 5,13,32 84 4-Decenal 11 2,4-Decadienal 13,32 78,84,85,89 Undecanal 5,10,13,20, 22,26 2-Undecenal 5,13,19,20, . 22,32 2,4-Undecadienal 13 Dodecanal 13,10 93 2-Dodecenal 13 2,4-Dodecadienal 13 Tridecanal 13,10 2-Tridecenal 13 Tetradecanal 10 Tetradecenal 13,10 Table 4 (cont'd.) 47 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pentadecanal 4,5,13,10 Hexadecanal 7,8,10 Heptadecanal 13,8 9-Octadecenal 11 Aromatic Benzaldehyde 4,6-8,10, 78,84,85,87 Sweet, almond-like 13,19-22 90-93 (4), Strong, sweet, almond (5), sweet- metallic (21) Benaladehyde, methyl 6 Benzaldehyde, 3-methyl 7,13 Benzaldehyde, methoxy 6 Benzaldehyde, ethyl 6,9,10 Benzaldehyde, 3-ethyl 28 Benzaldehyde, 4-ethyl 6 Benzaldehyde, 10 3-iSOpropyl Benzaldehyde, 11 4-isopropyl Cinnamaldehyde 13 Subtotal (%) 65 (9.5) 31 (12.3) KETONES Aliphatic, acyclic 2-Propanone 3-6,9,21,26, 78,82,85, Dull, meat-broth (3) (acetone) 29,30,32 89-92 40-42,70,72 2-Propanone, 1-phenol 6 87,91 2-Butanone 2,3,6,19-22, 87,90,92 Strong, grassy, sweet, 26,29,30,70 sickly, doughy (3), Sickly (21) 2-Butanone, 3-methyl 3,26,28 9O 2-Butanone,3,3- 91 dimethyl 2-Butanone, 3-hydroxy 4—8,10,13,20, Buttery (4) (acetoin) 22,26,70 2-Butanone, 4-phenyl 6 3-Buten-2-one, 87 4-phenyl 2,3-Butanedione 1,3-7,10,13, 90,92 Buttery (4), butter, 21,41,70 sickly (21) 2-Pentanone 3,5,6,21,23, 78,89,90,91 Buttery, sweet, 26,70 sickly, meaty (3), burnt, green (21) 3-Pentanone 22,23 Burnt, sickly (21) 2-Pentanone, 21,34 90 3-methyl Table 4 (cont'd.) 48 Chemical compound Beef Soy Odor descriptions volatile volatile (References) 2-Pentanone, 11,21 90,91 Cooked cabbage (21) 4-methyl 3-Pentanone, 9O 2-methyl 1-Penten-3-one 84 2,3-Pentanedione 13,21,39 84,85,92 2-Hexanone 6,21,23,26 78,89,90,92 3-Hexanone 9O 2-Hexanone, 3-methyl 4,5 2-Hexanone, 5-methyl 4,5,26 3-Hexanone, 5-methyl 26 2-Hexanone, 1-phenyl 26 4-Hexen-3-one 15 2-Heptanone 5,13,21 84,85,90-93 Green; pungent, sickly 21 3-Heptanone 13,21 90 2-Heptanone, methyl 10 2-Heptanone, 6-methyl 18 5-Hepten-2-one, 23 6-methyl 2-Octanone 4,5,10,13,21 84,85,90,91, Green, mushroom (21) 93 3-Octanone 13,21 84,90,92,93 4—Octanone 6-8,23 Octenone‘ 6 3-Octen-2-one 11 1-Octen-3—one 84 3,5-Octadien-2-one 92 2,3-Octanedione 13 84 2-Nonanone 5,6,10,13,21 90,91 Fatty (66), green (21) 3—Nonanone 7,8,26 4-Nonanone 28,26 5-Nonanone 26 2-Decanone 4,5,10,13, 90,91 Citrus (66) 21,70 5-Decanone 9O 2-Undecanone 5,13 90 Fruity (66) 4-Undecanene 5,6,13 2-Dodecanone 13 Waxy (66) 3-Dodecanone 7,8,13 2-Tridecanone 6,13 2-Tetradecanone 11 2-Pentadecanone 4,5,13,15 2-Hexadecanone 15 2-Heptadecanone 15 Table 4 (cont'd.) 49 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Aliphatic, cyclic Cyclopentanone, methyl 43 4-Cyclopentene, 1,3- 4,43 dione-4,5-dimethyl Cyclohexanone 10 Cyclohex-2-enone, 43 2-methyl Cyclohex-Z-enone, 43 4-methyl Cyclohex-2-enone, 43 2,6-dimethyl Cyclohex-Z-enone, 43 3,5,5-trimethyl Ionone (isomers) 4,5 Woody-berry, violet- like (5) Aromatic Acetophenone 6,10 Acetophenone, 44 2-hydroxy Acetophenone, 28 arylmethyl Acetophenone, 11 3-methoxy Methyl benzyl ketone 6 Butyl benzyl ketone 11 Methyl tolyl ketone 6,19 Methyl naphthyl ketone 11 Subtotal (%) 59 (8.5) 26 (10.3) ALCOHOLS Methanol 21,29,30,7O 81,84,89,90 Ethanol 4,5,7,8, 81,85,87,89, 19-21,30,41, 91-93 45,70 Ethanol, 2-ethoxy 5 Ethanol, 2-butoxy 4,5,13 9O Propanol 7,8,13 91,93 2-Propanol 19,21,22 90-92 Propanol, 2-methyl 7,8 90,92 2-Propanol, Z-methyl 7,8,31 9O l-Butanol 2,4,5.7,8, 90-93 13,19-21,7O 2-Butanol 44,46 Butanol, 2-methyl 6 Butanol, 3-methyl 6,7,9,19,20 81,89,92 2-Butanol, 2-methyl 85,92 2-Butanol, 2,3-dimethyl 5 Table 4 (cont'd.) 50 Chemical compound Beef Soy Odor descriptions volatile volatile (References) 2-Buten-1-ol, 5 3-methyl 3-Buten-2-ol, 5 3-methyl 2,3-Butanediol 12,13 Pentanol 4,5,7,8,10, 81,84,85,89-92 13,19-21,7O 2-Pentanol 81-89,92 Pentanol, 3-methyl 5 Pentanol, 4-methyl 5 1-Penten-3-ol 5,7,8,18, 84,85,90,92 Grassy, ethereal (5) 21,23 Hexanol 4,5,10,13,19-22 81,85,89-92 2-Hexanol 84,91-93 2-Hexanol, 3-methyl 11 2-Hexanol, 4-methyl 4,5 2-Hexanol, 5-methyl 5 Hexenol 6 2-Hexen-1-ol 7,8 3-Hexen-1-ol 6 2-Hexen-1-ol, 3-methyl 6 Heptanol 6,10,13,19, 81,89,93 20,22 2-Heptanol 27 92 3-Heptanol 13 4-Heptanol 13 1-Heptanol, 6-methyl 4,5 2-Heptanol, 4-methyl 11 2-Heptanol, 5-methyl 11 Octanol 5,7,8,10, 84,93 13,19,20,70 2-Octanol 92 3-0ctanol 5,13,15 84,92 4-Octanol 5,13,15 3-Octanol, 3-methyl 11 1-Octen-3-ol 4,5,7,8, 83-85,92,93 Heavy, metallic, fungal 10,21 (4), mushroom-like, slight metallic (5), mushroom, sickly, sweet (21) 2-Octen-1-Ol 5,13,15 84 2-Octen-3-ol 11 2-Octen-4-ol 5 Nonanol 10,15 84,93 3-Nonanol 11 4-Nonanol 5 1-Nonen-3-Ol 11 Decanol 10,15 51 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions volatile volatile (References) Undecanol 15 10-Undecen-1-ol 11,15 Dodecanol 15,70 Tridecanal 11 Tetradecanol 11 Pentadecanal 11 Hexadecanal 11 Octadecanol 11 4-Terpineol 11 Cyclopentanol 10,11 Benzyl alcohol 4-6,13 93 Benzyl alcohol, 11 2-methyl Phenethyl alcohol 16 Subtotal (%) 60 (8.5) 24 (9.5) PHENOLS Phenol 4-6,13 87 Phenol, 3-methyl 86 Phenol, 4-methyl 86,87 Phenol, 4-methyl-2,6-di- 18 91 t-butyl Phenol, 4-methyl-3,5-di- 10 t-butyl Phenol, ethyl 87 Phenol, vinyl 93 Phenol, 2-methoxy '85-87,93 Phenol, 4-ethyl-2- 87 methoxy Phenol, 2-methoxy-4-vinyl 85,93 Subtotal (%) 3 (0.4) 9 (3.6) CARBOXYLIC ACIDS Aliphatic, acyclic Methanoic (formic) 41 87 Ethanoic (acetic) 4,5,13, 80,87, 41,70 89,92 Ethanoic, 2-phenyl 87 Propanoic 7,41 80,87 Propanoic, 2-methyl 29,30,41,3O Propanoic, 3-phenyl 87 Butanoic 2,7,13,42,70 87 Butanoic, 2-methyl 13 Butanoic, 3-methyl 80,87 2-Butenoic 87 2-Butenoic, 2-methyl 87 Pentanoic 5 80,87 Table 4 (cont'd.) 52 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pentanoic, 2-methyl 52 Pentanoic, 4-methyl 52 8O Hexanoic 5,7,8,7O 80,84 Heptanoic 5 Octanoic 5 8O Nonanoic 5 8O Decanoic 32 8O Dodecanoic 32 Tetradecanoic 32 Pentadecanoic 32 Hexadecanoic 32 Heptadecanoic 32 9,12-Octadecadienoic 32 Aromatic Benzoic 87 Benzoic, 4-ethyl 87 Benzoic, 2-hydroxy 79 Benzoic, 4-hydroxy 79 Benzoic, 2,5,-dihydroxy 79 Benzoic, 4-hydroxy-3- 79 methoxy Benzoic, 4-hydroxy-3,5- 79 dimethoxy Cinnamic, 4-hydroxy 79 Cinnamic, 4-hydroxy-3- 79 methoxy Subtotal (%) 20 (2.9) 24 (9.5) ESTERS Methanoate (formate), 32 methyl Methanoate, ethyl 93 Methanoate, ethyl 4,5 91 Methanoate, hexyl 5 Methanoate, heptyl 5 Methanoate, octyl 11 Ethanoate (acetate), 92 methyl Ethanoate, ethyl 87,91-93 Ethanoate, butyl 92 Ethanoate, pentyl 5 81,89,92 Ethanoate, hexyl 5,11 84,92 Ethanoate, heptyl 11 92 Ethanoate, octyl 11 Ethanoate, acetol 15,23 Ethanoate, bornyl 5 Ethanoate, citronellyl 11 Ethanoate, terpinyl 11 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions volatile volatile (References) Propionate, butyl 91 Butanoate, pentyl—3- 11 methyl Butanoate, heptyl 11 Pentanoate, ethyl 5,23 Hexanoate, ethyl 5,11 Hexanoate, pentyl 84 Heptanoate, ethyl 5,11 Octanoate, ethyl 5,11 Nonanoate, ethyl 5,11 Decanoate, ethyl 11 Tetradecanoate, ethyl 11 Pentadecanoate, ethyl 11 Hexadecanoate, methyl 6,11 Hexadecanoate, ethyl 11 Heptadecanoate, ethyl 11 Octadecanoate, ethyl 5,11 Succinate, diethyl 11 Phthalate, diethyl 5 Phthalate, dibutyl 4,5 Salicylate, methyl 11 5,6-Dihydropyran-3,4- 48 dimethyl-6—carboxylic acid methyl ester Subtotal (%) 33 (4.7) 8 (3.2) LACTONES y-Butyrolactone 13 92 y-Crotonlactone 91 y-Butyrolactone, B-methyl 92 y-Butyrolactone, 50 Sulfur-like note of B-methylthia onions (50) y-Butyrolactone, 2-hydroxy- 50 3,3-dimethyl y-Pentalactone 6-8,13 92 O-Pentalactone 13 T-Pentalactone, methyl 7O 2-Pentenoic acid, 87 4-hydroxylactone 3-Pentenoic acid, 87 4-hydroxylactone Anhydromevalolactone 50,43 y-Hexalactone 4-6,13 O-Hexalactone 5,49 2-Hexenoic acid, 5 4-hydroxylactone 3-Hexenoic acid, 5 4-hydroxylactone 54 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions volatile volatile (References) y-Heptalactone 6,13 91 Sweet (66) O-Heptalactone 5,13 y-Octalactone 5,6,13 Oily (66) O-Octalactone 13 y-Nonalactone 5,13 84,93 Musk (66) O-Nonalactone 13 2-Nonenoic acid, 5 Deep-fat fried (5) 4-hydroxylactone 3-Nonenoic acid, 5 Deep-fat fried (5) 4-hydroxylactone y-Decalactone 13,51 Oin,)peachy, nut-like 66 O-Decalactone 6,13,51 Creamy, sweet, nut-like (66) v-Undecalactone 51 87 O-Undecalactone 51 y-Dodecalactone 6,51 O-Dodecalactone 6,51 y—Tridecalactone 51 O-Tridecalactone 51 y-Tetradecalactone 49,51 O-Tetradecalactone 49,51 y-Pentadecalactone 6 O-Pentadecalactone 49,51 y-Hexadecalactone 5 O-Hexadecalactone 5 y-Octadecalactone 49 Subtotal (%) 35 (5.0) 9 (3.6) FURANS Furan 19,23,70 87,90,92 Beany, grassy (50), sickly, nasty- smelling (21) Furan, 2-methyl 3,6,21, 90 Pleasant, slightly 23,70 sulfurous, meaty (3), sickly (21) Furan, 3-methyl 21,23,70 90 Furan, dimethyl 6,11 Furan, 2,5-dimethyl 6,11,21,23 9O Furan, trimethyl 6 Furan, 2—ethyl 3,6,9,23,7O 9O Acid, sour, whey butter-like (50) Furan, 2-methyl-5- 6,21,23 9O ethyl Furan, 2-propyl 3,4,6,11,21 9O Furan, 2-methyl-5- 9O propyl Furan, 2-propenal 9O 55 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions volatile volatile (References) Furan, 2-methyl- 21 propenal Furan, 2-butyl 6,21,23 9O Furan, 2-pentyl 3-9,13,21,23, 84,90,92 Licorice-like, beany- 70,74 greenish (5), green, pungent, sweet (21) Furan,2-pentyl 94 (cis and trans) Furan, 2-methyl-5- 9O pentyl Furan, 3-(4-methyl- 92 3-pentenyl) Furan, 2-hexyl 13,21,23 9O Furan, 2-hexenyl 21 Furan, 2-heptyl 6,13,23 Furan, 2-Octyl 13 Furan, 2-hydroxymethyl 28,70 Furan, 2-acetyl 5.6.47 87 Furan, 2-acetyl-5- 4-6 87 methyl Furan, 2-acetonyl 85 Furan, 2-propionyl 4 Furan, 2-acetyl-5- 87 propionyl Furan, dihydro 6 Furan, 2,3- 85 dihydrobenzo Furan, 2- 6 methyldihydrobenzo Furan, 2- 90 methyltetrahydro Furan, 2-phenyl 91 3-Furanone, dihydro- 52 5-methyl-4-hydroxy 3-Furanone, dihydro- 52 Caramel-like, burnt 2,5-dimethyl-4- pineapple (46,50), hydroxy Strawberry-like (dilute) (50) 3-Furanone, tetrahydro- 6-8,70 2-methyl Furfural (2-furaldehyde) 4-6,10, 85,87,91-93 15,26 2-Furfural, 5-methyl 5,6 85-87,93 Burnt, caramel-like, slightly meaty (50) Furfural, 5-methyl-2- 4,5,70 acetyl Table 4 (cont'd.) 56 Chemical compound Beef Soy Odor descriptions volatile volatile (References) 2-Furfural, 5,7,8 5-thiomethyl 2-Furylacetaldehyde 6 3-(2-Furyl)- 6 propionaldehyde 4-(2-Furyl)- 6 butan-Z-one Furfuryl alcohol 4,5 85,93 (2-Furyl)-ethanol 11 3-(2-Furyl)-propanol 6 2-Furan, carboxylic acid 87 Furoate, methyl 7O 2-Furoate, ethyl 11 Burnt, buttery, vanilla-like (50) 2-Furoate, allyl 11 2,2'-Difurfuryl ether 6 2,3-Difurfuryl ether 6 Furfuryl methyl ketone 15 Rum-like, radish (50) Subtotal (%) 41 (5.9) 26 (10.3) PYRIDINES Pyridine 4,5,9,10,41 Vile (concentrated) (4), bitter, pleasant, roasted (dilute) (4) Pyridine, methyl 3,10,28,70 Astringent, hazelnut- like (55) Pyridine, dimethyl 3 Pyridine, 3-ethyl-2,6- 7O dimethyl Pyridine, 2-ethyl 44 Green (68) Pyridine, 2-pentyl 44 Pyridine, 2-acetoxy 50 Pyridine, 2-carbonitrile 50 Pyridine, 1,6-naphtha 43 Nicotinate, methyl 50 Nicotinonitrile 50 Subtotal (%) 11 (1.6) O (O) PYRAZINES Pyrazine 3,5,65 85,86,88, 92,93 Pyrazine, 2-methyl 3-5,10,16, 85,86,88, Potato-like (4), 44,53,65, 91-93 roasted, nutty (68) Pyrazine, dimethyl 13 Pyrazine, 2,3- 16,10,44,65 85,86,88,93 Green, nutty (68) dimethyl Table 4 (cont'd.) 57 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pyrazine, 2,5- 4,5,10,16, 85,86,88, Potato-like (4), dimethyl 44,53,65, 91-93 roasted, earthy (5) Pyrazine, 2,6- 5,10,16,53, 86,88,91-93 Roasted, earthy (5) dimethyl 54,65,70 Pyrazine, trimethyl 10,16,44, 85,86,88, Nutty, roasted (68) 53,65 91,93 Pyrazine, tetramethyl 16,44,53,65 86,88 Pyrazine, 2-ethyl 3,16,44,65 92,93 Nutty, roasted (68) Pyrazine, ethyl methyl 70 Pyrazine, 3-ethyl-2- 53 Nutty, roasted (68) methyl Pyrazine, 6-ethyl-2- 16,24,65 methyl Pyrazine, 5-ethyl-2- 91 methyl Pyrazine, 2-ethyl-3- 85,88,93 methyl Pyrazine, 2-ethyl-5- 16,44,53,65 85,88,93 methyl Pyrazine, ethyl 7O dimethyl Pyrazine, 5-ethyl- 53,65 2,3-dimethyl Pyrazine, 3-ethyl- 15,16,44,47, 85,86,88 2,5-dimethyl 53,65 Pyrazine, 3-ethyl- 86,88,93 2,6-dimethyl Pyrazine, 2-ethyl- 15,53,65 Nutty, roasted (68) 3,5-dimethyl Pyrazine, 3,5,6- 3,53 86,88 trimethyl-Z-ethyl Pyrazine, 2,6-diethyl 47,65 93 Pyrazine, 2,3-diethyl- 3,65 Nutty, roasted (68) 5-methyl Pyrazine, 2,5-diethyl- 3,53,65 93 3-methyl Pyrazine, 2,6-diethyl- 44,65 3-methyl Pyrazine, 3,5-diethyl- 53,65 2-methyl Pyrazine, 3,6-diethyl- 65 2,5-dimethyl Pyrazine, triethyl 13,65 Pyrazine, 2-vinyl 65 Table 4 (cont'd.) 58 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pyrazine, 6-vinyl- 65 2-methyl Pyrazine, methylprOpyl 65 Pyrazine, 2,6- 3,53 dimethyl-3-propyl Pyrazine, 2,5- 91 dimethyl-N-propyl Pyrazine, isopropenyl 65 Pyrazine, propan-2-one 65 Pyrazine, isobutyl- 3 methyl , Pyrazine, t-butyl 13 Pyrazine, 2-acetyl 65 Popcorn (60,69) Pyrazine, 2-acetyl-5- 55,65 methyl Pyrazine, 2-acetyl-5- 65 ethyl Pyrazine, 6,7-dihydro- 65,75 5(H)-cyclopenta Pyrazine, 6,7-dihydro- 65,75 5(H)-cycl0penta-2- methyl Pyrazine, 6,7-dihydro- 65,75 5(H)-cyclopenta-5- methyl Pyrazine, 6,7-dihydro- 65,75 5(H)-cyclopenta-2 (or 3)-5-methyl Pyrazine, 6,7-dihydro- 75 5(H)-cyclopenta-2, 3-dimethyl Pyrazine, 6,7-dihydro- 75 5(H)-cyclopenta-2- ethyl-B-methyl Pyrazine, 6,7-dihydro- 75 5(H)—cyclopenta-2, 3,5-trimethyl Pyrazine, pyrrolo 9,65 Pyrazine, methylpyrrolo 76 Pyrazine, 3-methyl- 76 pyrrolo Pyrazine, 4-methyl- 76 pyrrolo Pyrazine, 2,3-di— 76 methylpyrrolo Table 4 (cont'd.) 59 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Pyrazine, 1,4- 76 dimethylpyrrolo Pyrazine, 3,4-di- 76 methylpyrrolo Subtotal (%) 50 (7.2) 17 (6.7) OTHER NITROGEN COMPOUNDS Ammonia 32,72,41 8O Amine, methyl 32 8O Amine, dimethyl 80,89 Pyrrole, 2-formyl 4,5,57 85,93 Pyrrole, 2-formyl- 85,86 I-methyl Pyrrole, 1-acetyl 93 Pyrrole, 2-acetyl 4,5,13,15 85,93 Unpleasant, plastic, antiseptic (4), unpleasant, heated plastic (18), weak, brown, fruit-pit (5) Pyrrole, N-methyl- 15 2-acetyl 2-Pyrrolidone, 1-propyl 87 Oxazole, 4,5-dimethyl 11 Oxazole, 2,4,5- 4,5 Nutty, sweet, green trimethyl (9) Oxazole, 2,4-dimethyl- 57 5-ethyl Oxazole, 2,5-dimethyl- 57 4-ethyl Oxazole, 2-isobutyl- 7O 4,5-dimethyl 3-Oxazoline, 2,4- 57,70 Nutty, vegetable (9) dimethyl 3-Oxazoline, 2,5- 11 dimethyl 3-Oxazoline, 2,4,5- 4,7,47,70 Woody, musty green (9) trimethyl 3-Oxazoline, 2,4- 57 Nutty, sweet, green, dimethyl-S-ethyl woody (9) 3-0xazoline,2,5- 57 Nutty, sweet, dimethyl-4-ethyl vegetable (9) 3-Oxazoline, 3,5- 43 dimethyl-2,4-dione Thiazole 12 Thiazole, 2-methyl 12 Green, vegetable (68) 60 Table 4 (cont'd.) Chemical compound Beef Soy Odor description volatile volatile (References) Thiazole, 4-methyl - 12 Thiazole, 2,4-dimethyl 12 Meat, cocoa-like (68) Thiazole, 2,4,5- 12 Cocoa, nutty (9,68) trimethyl Thiazole, 4-ethyl-2- 12 methyl Thiazole, 5-ethyl-4- 12 Nutty, green, earthy methyl (68) Thiazole, 5-ethyl-2,4- 12,70 Nutty, roasted, meaty dimethyl (9,68) Thiazole, 2,4-dimethyl- 12 Nut-like (50) 5-vinyl Thiazole, 4,5-dimethyl- 7O 2-propyl Thiazole, 5-ethyl-4- 7O methyl-Z-isopropyl Thiazole, 4-methyl-5- 11,12 (2-hydroxyethyl) Thiazole, 2-acetyl 4,5,12 Pleasant, popcorn-like, strong nutty, roasted (18), strong, nutty, cereal, pop— corn (50), pleasant, popcorn, strong, nutty, roasted (9), nutty, cereal, pop- . corn (68) Thiazole, benzo 4,5,10,12, 84 Slightly sweet, nutty, 13,15,70 roasted-brown, slightly popcorn-like , (18) Thiazole, methyl- 43,50 Fatty, smoky (50) thiobenzo 3-Thiazoline, 2,4- 53 Nutty, roasted, dimethyl vegetable (9) 2-Thiazoline, 2- 58 Freshly baked bread, acetyl bready (56) 3-Thiazoline, 2- 12,77 acetyl 3-Thiazoline, 2,4,5- 4,5,7,43,47 Meaty, nutty, onion (9) trimethyl Piperidine 85 Pyrimidine, 2,4- 43 dimethyl Table 4 (cont'd.) 61 Chemical compound Beef Soy Odor description volatile volatile (References) Pyrimidine, 4- 9,43 acetyl-Z-methyl Quinoxaline, 5,6,7,8- 65 tetrahydro Quinoxaline, 5,6,7,8- 65 tetrahydro—Z-methyl Subtotal ( 39 (5.6) 8 (3.2) SULFUR COMPOUNDS Hydrogen sulfide 9,21,29-32,41, 89,90,92 42,59,62 Mercaptan, methyl 12,21,29-31, 90 Sickly, sulfurous 41,42,59,65, cooked vegetable 70,62 (21) Mercaptan, ethyl 21,29-31,41, 9O 42,59,62 Mercaptan, propyl 31,41 90 Mercaptan, 2,2- 60 dimethylpropyl Mercaptan, butyl 8,42 Mercaptan, sec-butyl 61 Mercaptan, isobutyl 12 Mercaptan, t-butyl 59 Mercaptan, butyl-Z- 12 methyl Mercaptan, 2-butyl-3- 12 methyl Mercaptan, hexyl 61 Mercaptan, Heptyl 61 Mercaptan, octyl 59 Mercaptan, nonyl 59 Mercaptan, l-methyl- 12,39,59 Meaty odor (18), fresh thioethane onion (39) Mercaptan, benzyl 61 Mercaptan, naphthyl 12 Mercaptan, furfuryl 61 B-Methyl mercapto- 39 propionaldehyde (methional) Dimercaptan, 1,3- 61 prOpane Dimercaptan, 1,4- 61 butane Dimercaptan, 1,5- 61 pentane Dimercaptan, 1,6- 61 hexane Table 4 (cont'd.) 62 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Sulfide, dimethyl 6,8,9,13,21, 9O Sickly, sulfurous 29-31,41,42, (21) 70,62 Sulfide, ethyl 12,21 90 methyl Sulfide, diethyl 12 Sulfide, ethylene 21,23,59 9O Sickly, cooked cabbage, pungent (21 Sulfide, propylene 21,23 90 Sulfide, methyl 7,8 propyl Sulfide, methyl 9O iSOpropyl Sulfide, methyl 7,8,18,28 allyl Sulfide, ethyl 6 propyl Sulfide, diisopropyl 59 Sulfide, propyl 6,23 isooropyl Sulfide, diallyl 7,8 Sulfide, methyl butyl 6O Sulfide, ethyl butyl 6O Sulfide, ethyl isobutyl 61 Sulfide, dibutyl 61 Sulfide, methyl pentyl 6 9O Sulfide, dipentyl 61 Sulfide, diisopentyl 61 Sulfide, methyl octyl 59 Sulfide, methyl nonyl 59 Sulfide, methyl phenyl 60 Sulfide, benzyl methyl 59 Sulfide, vinyl phenyl 6O Sulfide, carbonyl 21,63,70 9O Sulfide, diacetyl 8 Thiothane, 1,1- 12 dimethyl Thioacetate, methyl 12 Thioacetate, ethyl 59 Thiopropionate, ethyl 6 Thioanisole 61 Disulfide, dimethyl 3,6,7,13, 90,92 Very strong, sulfurous, 19-21,31, garlic, onion 59.70 (3), sulfurous, sickly, cooked cabbage (21) Table 4 (cont'd.) 63 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Disulfide, ethyl 12,59,70 methyl Disulfide, methyl 12 vinyl Disulfide, diethyl 6,12,59 Disulfide, methyl 59 propyl Disulfide, methyl 59 isopropyl Disulfide, dipropyl 6,12 Disulfide, 61 diisoprOpyl Disulfide, dibutyl 61 Disulfide, di-sec- 17 butyl Disulfide, diisobutyl 61 Disulfide, di-t-butyl 59 Disulfide, dipentyl 61 bis(Methylthio)- 59 methane bis(Methylthio)- 64 ethane Disulfide, 1,3- 60,61 diethylene (1,3-dithiane) Disulfide, 1,4- 60,61 diethylene (1,4-dithiane) Disulfide, carbon 21,23,59,7O 90,91 Trisulfide 9O Trisulfide, dimethyl 21,59,61,7O Sulfurous, burnt, cooked cabbage (21) Trisulfide, methyl 59 ethyl Trisulfide, diethyl 59 Tetrasulfide, dimethyl 11,59 Sulfone, dimethyl 67 1,3,5-Trithiane, 12 Heated meat (50) 2,4,6-trimethyl (trithioacetaldehyde) ' 1,3,5-Trithiane, 12 2,2,4,4,6,6- hexamethyl (trithioacetone) 1,3-Dithiolane 6O 1,3-Dithiolane, 6O 2-methyl Table 4 (cont'd.) 64 Chemical compound Beef Soy Odor descriptions volatile volatile (References) 1,2,4-Trithiolane, 12,21,39, 90 Dry camphor (39) 3,5—dimethyl 47,65 1,3,4-Trithiolane, 7 2,5—dimethyl 1,2,4-Trithiolane, 12 3-ethyl-5-methyl 1,2,4-Trithiolane, 12 3-isoprOpyl-5- methyl 1-(2-Thienyl)-1- 12 propanone 1-(2-Methyl-5- 12 thienyl)-1- propanone Thiophene 12,21,59 9O Sickly, pungent (21) Thiophene, 2-methyl 3,6,9,12, 90 Green, sweet (21) 21,59,70 Thiophene, 3-methyl 23 9O Thiophene, 2,3- 21 dimethyl Thiophene, 2,5- 6,21,70 dimethyl Thiophene, 2-ethyl 6,12,30 9O Thiophene, 2-propyl 6 9O Thiophene, 2- 12 propenyl Thiophene, 5-methyl- 12 2-propyl Thiophene, 2-butyl 6,12 90 Thiophene, 2-dibutyl 91 Thiophene, 2-t-butyl 6O Thiophene, 3-t—butyl 6O Thiophene, 2-pentyl 6,12,21 90,91 Thiophene, 2-hexyl 6 Thiophene, 2-heptyl 6 Thiophene, 2-octyl 12 Thiophene, 2- 12 tetradecyl Thiophene, 3- 12 tetradecyl Thiophene, 2- 12 (hydroxymethyl) Thiophene, 2- 11 butanoyl Thiophene, 2— 6,11 heptanoyl Thiophene, 2- 11 octanoyl 65 Table 4 (cont'd.) Chemical compound Beef Soy Odor descriptions (References) Thiophene, 2- 4,7,12 Spicy, meat (18), carboxaldehyde 28,59 sharp, sweet, nutty, roasted grain-like (5) Thiophene, 3- 12 carboxaldehyde Thiophene, 2- 12 Cherry-like (50) carboxaldehyde-5- methyl Thiophene, 3- 56 carboxaldehyde-2,5- dimethyl Thiophene, 2-acetyl 6,12,59 Thiophene, 3-acetyl 12 Thiophene, 2-acetyl-5- 12 Onion-like, malty, methyl roasted (50) Thiophene, tetrahydro- 6O 2-methyl Thiophene, tetrahydro- 6O 2,5-dimethyl Thiophen-3-one, 12 tetrahydro Thiophen-3-one, 12 tetrahydro-Z-methyl Thiophenol 6O Thiophenol, 2-methyl 6O Thiophenol, 2,6- 60 dimethyl Thiophenol, 2-t-butyl 6O 1,3,5—Dithiazine, 5,6- 12 dihydro-2,4,6- trimethyl 1,3,5-Dithiazine, 12,39 perhydro-2,4,6- trimethyl (thialdine) Trithiepane 91 Subtotal (%) 127 (18.2) 24 (9.5) HOLOGENATED COMPOUNDS Carbon, tetrachloro 7O Methane, trichloro 4,5,18 (chloroform) Ethane, trichloro 7O 91 Ethane, tetrachloro 3 2-Propanol, 3 l-chloro Benzene, chloro 10,70 Table 4 (cont'd.) 66 Chemical compound Beef Soy Odor descriptions volatile volatile (References) Benzene, 1,4- 4,5,7,8,10 dichloro Benzene, 91 tetrachloro Biphenyl, 11 2-chloro Subtotal (%) 8 (1.1) 2 (4.0) MISCELLANEOUS COMPOUNDS Air 70 Carbon dioxide 70 92 Water 70 Ethyl isopropyl ether 5 Dipentyl ether 7 Diphenyl ether 11 1,1-Oimethoxyethane 5 1,1-Diethoxyethane 4,5 84 1,1-Oiethoxypropane 84 1,1-Diethoxy-n-hexane 11 84 1,1-Diethoxy-n-octane 11 1,1-Diethoxynonane 84 Methoxybenzene (anisole) 6 1,3-Diethoxybenzene 5 Methoxytoulene 6 Butylated hydroxyanisole 6 Butylated hydroxytoulene 6 Oimethyl pyrone 87 Pentyl pyrone 5,11 3-Hydroxy-2-methyl-4- 87 pyrone Cyanobenzene 11 Benzyl cyanide 11 Isomaltol 87 Coumarin 87 Methylcoumarin 87 Hexanonitrile 5 Hexamethyldisiloxane 7O Trimethylethoxy- 7O silane Trimethylsilanol 70 Hexamethylcyclo- 7O trisiloxane Octamethylcyclo- 7O tetrasiloxane Subtotal (%) 24 (3.4) 10 (4.0) Total (%) 697 (100) 252 (100) aR , eferences. 1. Merrit (1974) 48. Lee et al. (1981) 2. Sanderson et al. (1966) 49. Watanabe and Sato (1968a) 67 Table 4 (cont'd.) MacLeod and Coppock (1976) Peterson et al. (1975) Peterson and Chang (1982) Min et al. (1979) Hirai et al. (1973) Herz (1968) Laurie (1982) Mottram et al. (1982) Hsu et al. (1982) Wilson et al. (1973) Liebich et al. (1972) Maillard (1912) Watanabe and Sato (1972) Watanabe and Sato (1971) Holley (1978) Chang and Peterson (1977) Wicks (1963) Wicks (1965) Peterson and von Sydow (1973) Wicks et al. (1967) Peterson et al. (1973) Greenberg (1981) Wilson and Katz (1972) Uralets and Golovnja (1980) Piotrowski et al. (1970) Wong et al. (1975) Bender (1961) Bender and Ballance (1961) Self et al. (1963) Allen and Foegeding (1981) Cho and Bratzler (1970) Yamato et al. (1970) Giacino (1970) Hoffman and Meijboom (1968) Nixon et al. (1979) Brinkman et al.(1972) Kramlich and Pearson (1960) Yueh and Strong (1960) Brennan and Bernhard (1964) Flament et al. (1978) Watanabe and Sato (1971b) Bailey and Swain (1973) Hodge (1967) Chang et al.(1968) Ohloff and Flament (1978b) Watanabe and Sato (1968b) Tonsbeek et al. (1968) Flament and Ohloff (1971) Park et al. (1974) Ho et al. (1983) Mussinan and Walradt (1974) Mussinan et al. (1976) Tonsbeek et al. (1971) Golvnja and Rothe (1980) Garbusov et al. (1976) Shankaranarayana et al. (1982) Takken et al. (1976) Grey and Shrimpton (1967) Hartman et al. (1984) Mussinan et al. (1973) Arctander (1969) Shankaranarayana et al. (1975) Pittet and Hruza (1974) Robert (1964) Galt and MacLeod (1984) Lillard and Ayres (1969) Hornstein et al. (1960) Qvist and von Sydow (1976) Nonaka et al. (1967) Flament et al. (1976) Flament et al. (1977) Evers (1976) Fujimaki et al. (1965) Arai et al. (1966a) Arai et al. (1966b) Arai et al. (1967) Sessa et al. (1969) Badenhop et al. (1969) Wilkens et al. (1970a) Wilkens et al. (1970b) Manley et al. (1970a) Manley et al. (1970b) Maga et al. (1973) Cowan et al. (1973) Qvist and von Sydow (1974) Palkert (1980) Rosario et al. (1984) Kato et al. (1981) Arai et al. (1970) 68 Sulfur-containing compounds (18.2%), hydrocarbons (17.5%), followed by aldehydes (9.5%), alcohols (8.6%) and ketones (8.5%) make up the largest proportion (62.5%) of the cooked beef volatiles. Chemical Nature and Relative Contribution of Volatiles to Cooked Beef Aroma Cooked beef volatiles with varying degrees of solubility in water, are present in low concentrations, and give rise to a variety of odor sensations (MacLeod and Seyyedain-Ardebili, 1981). In contrast to the non-volatiles, few are essential intermediates in the biochemistry of the animal (Schutte, 1976). With minor variations, the composition of all meat is similar and this is reflected in the volatile compounds isolated from different cooked meat samples (Dwivedi, 1975; Shahidi et al., 1986). Thus far, no single compound uniquely responsible for cooked beef aroma has been identified, although some have been described as meat- like (Table 4, Wasserman, 1979). According to Wasserman (1979), direct evidence for the involvement of individual chemical compound in cooked beef aroma is difficult to glean from the literature for the following reasons: 1 No true character impact compounds exist; 3 ( I (2) Very few studies have been quantitative; ( ) Threshold values for all compounds are not available; and ( ) 4 Additive, antagonistic, and synergistic effects occur. Characteristically, cooked beef aroma is subdivided into boiled and roasted beef aroma. Boiled beef aroma is produced in the presence of water whereby the temperature during boiling does not exceed 100°C; 69 whereas, roasted beef aroma is liberated under relatively drier heating conditions whereby the temperature rises well above 100°C (Wasserman, 1979). The summarized comparison of boiled versus roasted beef volatiles by MacLeod and Coppock (1977) reveals that except for aliphatic amines and carboxylic acids, thiols, dithianes, dithiolanes, trithiolanes and hydantoins, all other chemical classes have been more frequently identified in roasted than in boiled beef aroma. Min et al. (1979) studied the volatile compounds in the neutral fraction of roast beef. Due to the powerful odor characteristics and relatively large numbers of lactones, substituted aromatics, furans, and sulfur compounds, these classes Of compounds were considered to be important contributors to roast beef flavor. Chang and Peterson (1977) listed carbonyl compounds, aliphatic and aromatic hydrocarbons, saturated alcohols, esters and ethers as classes which, in their opinion, may not be primary contributors to beef flavor. They also listed classes of compounds that they believed to be important. These include lactones, furanoid or hydrofuranoid compounds, acyclic sulfur-containing compounds, and heterocyclic compounds containing sulfur, nitrogen, and oxygen. Schutte (1974) suggested that carbonyls, heterocyclics, and, sulfur- and nitrogen-containing compounds, as well as some phenols, are the most important contributors to beef flavor. Bodrero et al. (1981) concluded that sulfur compounds and nitrogen and oxygen heterocyclics are the most important groups contributing to beef aroma. A number of compounds identified in beef flavor volatiles have been described when isolated from meat systems. However, some have apparently 70 been described independently since the food system was not specified (Table 4). Many of the odor descriptions have been assigned by the investigators in a purely subjective fashion without resorting to acceptable methods of sensory evaluation. Nevertheless, Table 4 permits some interesting observations. Various terminologies were used by different researchers to describe a particular compound as in the case for hexanal, benzaldehyde, 3-methylbutanal, and l-octen-3-Ol. While the descriptions given for 1-octen-3-ol provide similar impressions, compounds such as 2-methylfuran and 2-acetylpyrrole have been given conflicting descriptions. 1-Octen-3-ol, for example, has been described as mushroom, sickly and sweet (Persson and von Sydow, 1973), mushroom, slightly metallic note (Peterson and Chang, 1982), and heavy metallic and fungal (Peterson et al., 1975). 2-Methylfuran has been described as sickly (Persson and von Sydow, 1973), and pleasant, slightly sulfurous, and meaty (MacLeod and Coppock, 1976). Both description pertain to the compound as evaluated in beef. As pointed out by Shahidi et al. (1986), relatively few of the compounds identified in beef volatiles have so far been described organoleptically. Not more than a dozen compounds have been organoleptically described by two or more research workers. NO alcohols, acids, or esters have been evaluated. In general, pyrazines frequently have roasted/burned/grilled, nutty, green or earthy aroma (Pittet and Hruza, 1974; Ohloff and Flament, 1978a). Several members of the oxazoles, oxazolines, thiazoles and thiazolines have been described as nutty. Other odor descriptions frequently associated with the oxazoles and oxazolines are sweet, green, woody, musty, and vegetable-like (Mussinan et al., 1976). Some thiazoles 71 and thiazolines (2,4-dimethylthiazole, 2,4-dimethyl-5-ethylthiazole, trimethylthiazoline), however, have meaty odors (Pittet and Hruza, 1974; Mussinan et al., 1976). Many Strecker aldehydes contribute to "browned", roasted, and toasted aromas (Self et al., 1963; Hodge et al., 1972). Thiophenes are also believed to contribute roasted notes in meat (Maga, 1975). Diacetyl and acetoin are considered to provide a buttery note to cooked meat (Hirai et al., 1973; Peterson and Chang, 1975). Persson and von Sydow (1973) demonstrated that certain carbonyl and sulfur compounds are responsible for the high heat (retort) off-flavor of canned beef. Chang and Peterson (1977) suggested that 2-formyl- pyrrole, 2-acetylpyrrole and benzothiazole may contribute to the retort flavor of canned beef stew. MacLeod and Coppock (1977) provided evidence that carbonyl compounds (particularly 2-methylbutanal), sulfides and also pyrroles and pyridines are probably important in roasted aromas of heated beef and tentatively suggested that benzenoids and furans may contribute to the desirable qualities associated with well-cooked beef. There are a number of sulfur compounds (Table 5) that have been synthesized and are described as having meat Odor characteristics. None of these has been found in meat volatiles (May, 1974; D'Souza, 1984). It is therefore evident that the cooked meat aroma profile is due to the sum of all sensory effects produces simultaneously at the Olfactory epithelium by a large number of volatiles of different structures present in a particular quantitative proportion (MacLeod and Coppock, 1977; Ohloff and Flament, 1978b; Rhodes, 1979). 72 Table 5. Compounds possessing meaty notes . Chemical compounds Aroma notes (References)a Furan 4-Mercapto-2-methyl- 4,5-Dihydrofuran 3-Mercapto-2-methyl- Tetrahydrofuran 4-Mercapto-3-oxo- 4-Mercapto-5-methyl-3-oxo- Furanone 4-MercaptO-5-methyl-3(2H)- Mercaptan Pyrazinyl methyl Thiol 2-Ethylbenzene- 2-Methyl-3-furan- Pyrazine methane- Thiophene 3-Mercapto-2-methyl- 2,3-Dihydrothiophene 3-Mercapto-2-methyl- 3-Mercapto-4-hydroxy-2~methyl- 4,5-Dihydrothiophene 3-Mercapto- 3-Mercapto-2-methyl . 4-MercaptO-2-methyl- Tetrahydrothiophene 3-Mercapto-2-methyl- 4-Mercapto-2-methyl- Green, meaty, herbaceous (1,2) Roasted meat (1,2) Green, meaty, maggi-like (1,2) Meaty, maggi-like (1,2) Sweet, meat-like (2) Roasted meat-like (1) Burnt, meatlike (1) Roasted meat (1) Roasted meat (1) Roasted meat (1,2) Sweet, roasted meat (1,2) Meaty, savory (2) Meaty (2) Meaty (2) Roasted meat (2) Meaty (2) Meat-like (2) aReferences: 1. Chang and Peterson (1977). 2. van den Ouweland and Peer (1975). 73 Comparison of Beef and Soy Volatiles Unlike cooked beef aroma, hydrocarbons (13.5%), aldehydes (12.3%), ketones and furans (10.3% each) are more frequently identified in SPP than the sulfur-containing compounds (9.5%) (Table 4). In comparison, relatively little research effort has been expended in the characteri- zation of volatile components in heated/raw SPPs. Some 252 compounds have been identified in the volatile fractions of SPP. In general, heating causes an increase in the concentrations of soy volatiles. Kato et al. (1981) examined the changes in the volatile components of soybeans during roasting (200°C for 10-30 min). They found that the major volatile components of raw soybeans, such as n-hexanol, l-octen- 3-ol and n—hexanal, decreased during the course of roasting, but the rate of decrease was not rapid. During roasting, alkylated pyrazines, oxygenated furans and pyrroles, and phenols were formed or increased markedly. Sensory evaluation showed that a flavor change to desirable from "beany" or "objectionable" occurred between 10-20 min of roasting. These results suggested that the roasted flavor (possible contributors may be 2-ethyl-5- (and 3-) methyl-pyrazine) may have masked the "beany" flavor in soybean. Hrdlicka and Cuba (1971) studied the changes in sulfur-containing compounds when heating soy protein with glucose. They found an increase of the total amount of such compounds with increasing temperature and/or heating time. More recently, Rosario et al. (1984) in their comparison of head- space volatiles from winged beans and soybeans revealed that raw soybean volatiles contained a significant amount of methyl substituted 1—butanols, pentanol, hexanol, 2-/3-Octanol, and l-Octen-3-ol, and few 74 furans, pyrazines, sulfur compounds and terprenoids. On heating, the concentration of nearly all compounds decreased except for pentanal, hexanal, 2-heptanone, 1-penten-3-ol, 1-Octen-3-ol, 2-pentylfuran, methylpyrazine, 2,5- and 2,6-dimethylpyrazine. These results are in disagrement with those of Hrdlicka and Cuba (1971), Qvist and von Sydow (1974) and Kato et al. (1981). Qvist and von Sydow (1974) offered the only report comparing the similarities and dissimilarities Of the volatiles isolated from heated beef and heated soy isolate (Promine D). The authors reported that although aldehydes are important in both samples, the concentrations of butanal, pentanal, and hexanal are much higher in heated soy isolate. The important branched—chain aldehyde, 2-methylpropanal is about four times more abundant in heated soy isolate than in heated beef. More furans were detected in the heated Promine 0 sample and the concentra- tions of those present in both samples were generally higher in the heated soy protein sample. On the other hand, hydrogen sulfide, methanethiol, ethanethiol, dimethylsulfide, and ethylene sulfide are present in larger concentrations in heated beef; whereas, methyldisulfide and thiOphene are generally somewhat higher in concentration in the soy sample. In general, the concentrations of almost all volatiles (except alcohols) increased on heating, independent of protein source. A number of new compounds (particularly sulfur compounds) are detected in heated samples. Based on odor threshold data and experience from samples Of heat sterilized beef, Qvist and von Sydow (1974) concluded that the odor of all heated samples depends on the presence of low molecular weight 75 branched-chain aldehydes and sulfur compounds. Several straight-chain aldehydes and several furan derivatives are particularly important to flavor in the heated soy isolate. Flavorinngextured Soy Protein Products Meat Flavor System An array of meat flavors (beef, chicken, bacon, ham, and pork) based on hydrolyzed proteins and including the appropriate precursors required for heat-generated flavors are available in liquid, paste, or spray dried states (Gutcho, 1977). In general, the precursors for these flavors consist of an amino and/or sulfur source on the one hand, and reducing sugars or carbonyl compounds on the other (Manson and Katz, 1976; Schutte, 1976). According to MacLeod and Seyyedain-Ardebili (1981) and Gutcho (1977), these commonly include: (1) Amino acids/peptides/nucleotides glycine, B-alanine, aspartic and glutamic acid, lysine, histidine, proline, glutathione, and 5'-nucleotides; (2) Protein hydrolyzates hydrolyzed vegetable protein, defatted cod fish flesh, casein, whey, ground nut, egg, yeast, blood and liver hydrolyzates; (3) Sulfur-containing compounds or hydrogen sulfide releasing agents cysteine, thiamine, hydrogen sulfide, methionine, taurine, egg protein, vegetable extract, organic thiols and sulfides, inorganic sulfides, thiocarbonates, thioamides, 2-mercapto- alkanoic acids and their amides, mercaptoalkylamines, mercapto- alcohols, and S-acetylmercaptosuccinic acid; (4) Sugars and carbonyl compounds arabinose, glucose, fructose, lactose, ribose, xylose, ribose-5- phosphate, hydrolyzed polysaccharides, yeast autolyzate/hydro- lysate, aliphatic aldehydes, ketones, nucleotide carbohydrate, ascorbic/isoascorbic acid, furanones or their precursors, and carboxylic acids; (5) Fats beef fat, edible fat, coconut oil, triglyceride, fatty material, and fatty acids; 76 (6) Solvents, and, water, glycerol, propan-1,2-diol, ethanol, and ethandiol; (7) Flavor adjuvants stabilizers, thickeners, surface active agents, conditioners, flavorants, and flavor intensifiers. The commonly used sulfur-containing compounds have been cysteine, thiamine, and hydrogen sulfide. Cysteine is the paramount source of sulfur-containing volatiles and is active either in the free form or within the tripeptide glutathione or as part of proteinaceous materials such as hydrolyzed vegetable protein (MacLeod and Seyyedain-Ardebili, 1981). Of all the amino acids occurring naturally in meat, cysteine and cystine yield the meatiest odors when subjected to thermal processing (Wilson, 1975). Wilson (1975) also considered the relevance of methionine and taurine in processed meat flavors. The use of methionine is limited to flavors in which the "potato skin" odor of methional (Strecker aldehyde) and the "green vegetable” Odor Of methanethiol and dimethyldisulfide are either suppressed, tolerable, or desired (Wilson, 1975). Methionine is the preferred amino acid for pork flavor (Gutcho, 1977). Taurine (2-aminoethanesulfonic acid) present in natural meat extract at m1.2-1.5% by weight on a dry basis (Gutcho, 1973) appears in several patents but its role is uncertain (Wilson, 1975). Carbonyl compounds supply a roasted burned note which is both highly desirable and also difficult to obtain in their absence (Wilson, 1975). Pentoses are more reactive than hexoses (May, 1974; Gutcho, 1977); sugar phosphates are more reactive than sugars (Manson and Katz, 1976). Strecker degradation perpetuates the supply of carbonyl compounds in 77 the form of Strecker aldehydes. In 1980, Hsieh et al. using surface response methodology, developed a synthetic model meat flavor system consisting of an autoclaved mixture of three simple sugars (glucose, xylose, and ribose), ten amino acids (glycine, alanine, monosodium glutamate, cysteine hydrochloride, methionine, taurine, leucine, isoleucine, serine, and arginine), inosine-5'-nucleotide, guanosine-5'-nucleotide (optional), glyco- protein, salt, and fat (optional). The meat flavor produced is claimed to be equal to or superior to commercial meat flavor extracts and nearly equal to authentic beef extracts. A closely parallel system developed by Schrodter and Wolm (1980) consisted of glucose and nine amino acids (aspartic and glutamic acid, histidine, alanine, glycine, serine, proline, arginine, and cysteine-hydrochloride). The optimized model was characterized by very high amounts of aspartic and glutamic acid, arginine and proline. Of increasing importance in formulating meat flavorings are meat flavor-contributing chemicals (mercaptofurans and mercaptothiophenes) which have not yet been identified in natural meat aroma (van den Ouweland and Peer, 1978). Because of the complexity of meat flavor and incomplete knowledge, a genuine fascimile has not yet been produced. Methods of Flavoring Thermally-induced meat flavors may be added to TSP before or after texturization. Numerous methods have been suggested and utilized for the flavoring of TSP. These include: pre-extrusion flavor addition, flavor development from precursors during extrusion, and post-extrusion 78 flavor addition. Combinations of two or more of these methods are also used (Fischetti, 1975; Palkert, 1980; Kinsella, 1983). Post-extrusion Flavor Addition Currently, flavor addition most commonly occurs post-extrusion (Blanchfield and Ovenden, 1974; Pagington, 1975; Williams et al., 1977a). This involves: (1) hydrating the TSP in a flavor medium followed by drying,cn~(2) spraying an oil and flavor mixture onto the dried TSP (Pagington, 1975). Post-extrusion flavor addition suffers from the disadvantage of involving an additional processing step and thus would be considerably more expensive than pre-extrusion addition of flavor compounds or flavor precursors. Also, post-extrusion added flavorings are very prone to loss during storage (Blanchfield and Ovenden, 1974). Additionally, the hydration method is prone to flavor loss through leaching, while the surface flavor addition method results in uneven distribution Of the flavors (Fischetti, 1975). Pre—extrusion Flavor Addition On the other hand, pre-extrusion flavor addition is the simplest and cheapest method of flavor addition (Blanchfield and Ovenden, 1974; Fischetti, 1975; Pagington, 1975). This method yields a homogeneously flavored product which probably suffers little flavor loss during storage (Pagington, 1975). However, at present pre—extrusion flavoring yields an unsatisfactory flavored product and considerable flavor loss apparently occurs during extrusion (Pagington, 1975; Williams et al., 1977a). 79 Palkert (1980) studied the effect of extrusion processing upon flavor retention in pre-extrusion flavored TSP using a Tenax trapping system. The synthetic meat flavors consisted of C3-C4 sulfides, C2-C4 disulfides, heterocyclics (2,4-dimethylthiazole, 2,5-dimethylthiophene, furfural and pyrrole), and undecanal. The author reported that the die temperature of the extruder from 205-230°C had little effect upon flavor retention. In contrast, decreasing the third barrel temperature from 205°C to 180°C reduced flavor retention by more than half. Palkert (1980) attributed the reduction in flavor recovery to the highest density of the low temperature extruded sample which inhibited flavor migration during sampling. Interacting the synthetic meat flavors with soy flour in the presence of water prior to extrusion, slightly increased the flavor retention. Drying TSP under conditions which reduced its moisture content from 10% to 3.5% resulted in little loss of the flavor compounds, with the exception of furfural. Furfural, however, is known to polymerize rapidly even at room temperature (Noller, 1966). Its loss during drying was probably due to polymerization rather than volatilization. In general about 90% of the pre-extrusion added flavor compounds could not be recovered following extrusion. The recovery of the compounds ranged from 4-22%, with the nitrogen-containing heterocyclics: pyrrole (20%) and 2,4-dimethylthiazole (22%), being recovered to a much greater extent than the rest. However, there was no obvious relationship between molecular structure and their recovery following extrusion. According to Palkert (1980), processes causing the loss of pre- extrusion added flavor compounds during processing include (Palkert, 80 1980); (a) Thermal degradation, oxidation, and polymerization of the added flavor compounds during extrusion; (b) Reaction of the added flavor compounds with soy flour components during extrusion; and, (c) Volatilization of the flavor compounds during extrusion or post- extrusion during drying of the TSP. Except for the effect of post-extrusion drying, the quantitative effects of these processes are difficult to determine (Palkert, 1980). Pre-extrusion Addition of Flavor Precursors The use of flavor precursors which react with one another or with soy flour components during extrusion forming desirable flavor compounds has been suggested by many workers (Coleman, 1975; Hashida, 1974; Heath, 1972; Pagington, 1975; van den Ouweland and Schutte, 1978; Schutte and van den Ouweland, 1979; Kinsella, 1983). However, many difficulties arise in this method from the fact that the Optimum conditions for TSP productions are narrow and do not correspond to those for flavor development (Blanchfield and Ovenden, 1974). Additionally, Maillard reactions used for the production of meat flavors are open ended and undesirable flavors can also develop during storage (Blanch- field and Ovenden, 1974; Heath, 1972). The pre-extrusion addition of flavor precursors has the advantage of not involving an addition processing step as is the case of post- extrusion flavor addition. It also has the unique potential of yielding flavors characteristic of the degree of doneness of the meat to which the flavored TSP has been added (Heath, 1972). van den Ouweland and Schutte (1978) reported that the pre-extrusion addition of a well balanced mixture of carbonyls (glycoaldehyde, gloxal, 81 pyruvaldehyde, dihydroxyacetone, glyceraldehyde, acetoin, diacetyl and hydroxydiacetyl) or an Amadori compound and hydrolyzed vegetable protein/yeast autolysates generated a meaty background in TSP. Additionally, the meaty background may be intensified with the use of two meat flavor-generating reactions. The first one is an interesting example of the say in which amino acids can act as flavor precursors for the formation of l-methylthioethanethiol. The formation of this compound has been described by Schutte and Koenders (1972) with the net result being as follows: SH I CH3CHO + CH3SH + H23 + CH3 - c - s - CH3 I H References Allen, C.E. and Folgeding, E.A. 1981. Some lipid characteristic and interactions in muscle foods - A Review. Food Tech. 35:253. Anjou, K. and von Sydow, E. 1967. The aroma of cranberries. II. Vaccinium macrocarpon. Acta Chem. Scand. 21:2076. Arai, S., Noguchi, M., and Kaji, M. 1970. N-Hexanal and some volatile alcohols, their distribution in raw soybean tissues and formation in crude soybean concentrate by lipoxygenase. Agric. Biol. Chem. 32:1420. Arai, S., Suzuki, H., Fujimaki, M., and Sakurai, Y. 1966a. Studies on flavor components in soybean. Part 1. Phenolic acids in defatted soybean flour. Agric. Biol. Chem. 30:364. Arai, S., Suzuki, H., Fujimaki, M., and Sakurai, Y. 1966b. Studies on flavor components in soybean. Part 3. Volatile fatty acids and volatile amines. Agric. Biol. Chem. 30:863. Arai, S., Suzuki, H., Fujimaki, M., and Sakurai, Y. 1967. Studies on flavor components in soybean. Part 4. Volatile neutral compounds. Agric. Biol. Chem. 31:868. 82 Arroyo, P.T. and Lillard, D.A. 1970. Identification of carbonyl and sulfur compounds from nonenzymatic browning reactions of glucose and sulfur-containing amino acids. J. Food Sci. 35:769. Arctander, S. (Ed.). 1969. "Perfume and Flavor Chemicals," Vol. 11. Published by the author, Montclair, NJ. Aspelund, T.G. and Wilson, L.A. 1983. Adsorption of off-flavor compounds onto soy protein: A thermodynamic study. J. Agric. Food Chem. 31:539. Aspelund, T.G. and Wilson, L.A. 1979. "World Soybean Conference 11,” F.T. Carlin (Ed.), p. 32, Westview Press, Boulder, CO. Badenhop, A.F., Wilkens, W.F. 1969. Formation of 1-octen-3-Ol in soybeans during soaking. J. Am. Oil Chem. Soc. 46:179. Bailey, M.E., and Swain, J.W. 1973. Influence of nitrite on meat flavor. Proc. Meat Ind. Res. Conf., Am. Meat Institute Foundation, Chicago, p. 29. Baltes, W. 1980. Significance Of the Maillard reaction on the development of flavor in foods. Lebensm. Gerichtl. Chem. 34:39. Bauer, C. and Grosch, W. 1977. The taste of di-, tri-, and tetra- hydroxy fatty acid. Z. Lebensm. Unter. Forsch. 165:82. Bender, A.E. 1961. A preliminary examination of some of the compounds responsible for meat flavor. Chem. Ind. (London) p. 2114. Bender, A.E. and Ballance, P.E. 1961. A preliminary examination of the flavor of meat extract. J. Sci. Food Agric. 12:683. Berry, B.W., Leddy, K.F., and Bodwell, C.E. 1985. Sensory characteris- tics, shear values and cooking properties of ground beef patties extended with iron and zinc-fortified soy isolate, concentrate or flour. J. Food Sci. 50:1556. Beyeler, M. and Solms, J. 1974. Interaction of flavor model compounds with soy protein and bovine serum albumin. Lebensm. Wiss. U. Tech. 7:217. Bird, K.M. 1974. Plant proteins in USDA feeding programs. Cereal Sci. Today 19:226. Blanchfield, J.R. and Ovenden, C. 1974. Problem of flavoring extruded snack foods. Food Manufacture, Jan., p. 27. Bodrero, K.O, Pearson, A.M., and Magee, W.T. 1981. Contribution of flavor volatiles to the aroma of beef by surface response methodology. J. Food Sci. 46:26. 83 Bodwell, C.E. 1983. Effects of soy protein on iron and zinc utiliza- tion in humans. Cereal Food World 28:343. Brennan, M.J. and Bernhard, R.A. 1964. Headspace constituents of canned beef. Food Tech. 18:743. Brinkman, H.W., COpier, H., deLeuw, J.J.M., and Tjan, 5.8. 1972. Components contributing to beef flavor: Analysis of the headspace volatiles of beef broth. J. Agric. Food Chem. 20:177. Chang, S.S. 1979. Flavor and flavor stability of foods. J. Am. Oil Chem. Soc. 56:908. Chang, S.S. and Peterson, R.J. 1977. Recent developments in the flavor of meat. J. Food Sci. 42:298. Chang, S.S., Hirai, C., Reddy, B.R., Herz, K.O., Kato, A., and Sipma, G. 1968. Isolation and identification of 2,4,5-trimethyl-3-oxazoline and 3,5-dimethyl-1,2,4-trithiolane in volatile flavor compounds of boiled beef. Chem. Ind. (London) p. 1639. Ching, J.C.-Y. 1979. Volatile flavor compounds from beef and beef constituents. Ph.D. dissertation, Univ. of Missouri, Columbia, MO. Cho, 1.6. and Bratzier, L.T. 1970. Effect of sodium nitrite on flavor of cured pork. J. Food Sci. 76:668. Chuyen, N.V., Kurata, T., and Fujimaki, M. 1973. Studies on the reactions of dipeptides with glyoxal. Agric. Biol. Chem. 37:327. Cowan, J.C., Rackis, J.J., and Wolf, W.J. 1973. Soybean protein flavor components: A review. J. Am. Oil Chem. Soc. 50:426A. Crocker, E.C. 1948. The flavor of meat. Food Res. 13:179. Damodaran, S. and Kinsella, J.E. 1981a. Interaction of carbonyls with soy protein: Thermodynamic effects. J. Agric. Food Chem. 29:1249. Damodaran, S. and Kinsella, J.E. 1981b. Interaction of carbonyl with soy protein: Conformation effects. J. Agric. Food Chem. 29:1253. Danehy, J.P. 1986. Maillard reactions: Nonenzymatic browning in food systems with special reference to the deVelopment of flavors. Food Res. 30:77. Dawes, I.W. and Edwards, R.A. 1966. Methyl substituted pyrazines as volatile reaction products of heated aqueous aldose, amino acid mixtures. Chem. Ind. (London) p. 2203. del Rosario, R., de Lume, 8.0., Haber, T., Flath, R.A., Mon, T.R., and Teranishi, R. 1984. Comxarison of headspace volatiles from winged beans and soybeans. J. gric. Food Chem. 32:1011. 84 D'Souza, L.A. Meat flavor volatiles: A review Of the composition, techniques of analysis and sensory evaluations. M.S. thesis, Univ. of Toronto, Toronto, Canada. Outton, H.J. 1980. Flavor problems in the usage of soybean Oil and meal. ACS Symp. Series No. 75:81. American Chemical Society, Washington, DC. Dwivedi, B.K. 1975. Meat flavor. CRC Crit. Rev. Food Tech. 5:487. Eldridge, A.C., Friedrich, J.P., Warner, K., and Kwolek, W.F. 1986. Preparation and evaluation of supercritical carbon dioxide defatted soybean flake. J. Food Sci. 51:584. Eskin, N.A.M., Grossman, S., and Pinsky, A. 1977. Biochemistry of lipoxygenase in relation to food quality. CRC Crit. Rev. Food Sci. Nutr. 9:1. Fischetti, F. 1975. Flavoring textured soy proteins. Food Prod. Dev. 9(6):64. Flament, I. 1976. Sur l'arome de bouef grillee. II. Helv. Chim. Acta. 59:2308. Flament, I. and Ohloff, G. 1971. Recherches sur les aromes, 18e communication (1) sur l'arome de viande de bouef grillee. I Pyrazine. Helv. Chim. Acta. 54:1911. Flament, I., Sonnay, P., and Ohloff, G. 1977. Sur l'arome de viande de boeuf grillee. III. Pyrrolo[1,2-a;I-pyrazines identification et synthese. Helv. Chim. Acta. 60:187 . Flament, I., Willhalm, B., and Ohloff, G. 1978. New developments in meat aroma research. In "Flavor of Foods and Beverages , Chemistry and Technology," G. Charalambous and G.E. Inglett (Ed.), p. 15. Academic Press, NY. Franzen, K.L. and Kinsella, J.E. 1974. Parameters affecting binding of volatile flavor compounds in model food systems. 1. Proteins. J. Agric. Food Chem. 22:675. Friedrich, J.P. and Eldridge, A.C. 1985. Defatted soybean products by supercritical fluid extraction. US Patent 4493854. Friedrich, J.P. and List, G.R. 1982. Characterization of soybean oil extracted by supercritical C02 and hexane. J. Agric. Food Chem. 30: 192. Friedrich, J.P. and Pyrde, E.H. 1984. Supercritical C0 extraction of lipids from lipid bearing materials and characteriza ion of the product. J. Am. Oil Chem. Soc. 61:223. 85 Fujimaki, M. 1969. Fundamental investigations of proteolytic enzyme application to soybean protein in relation to flavor. Dept. Agric. Chem., Univ. of Tokyo, USDA Final Report, Ur-All-(40)—8. Fujimaki, M., Arai, S., Kirigaya, N., and Sakurai, Y. 1965. Flavor components in soybean. I. Aliphatic carbonyl compounds. Agric. Biol. Chem. 29:855. Galt, A.M. and MacLeod, G. 1984. Headspace sampling of cooked beef aroma using Tenax GC. J. Agric. Food Chem. 32:59. Garbusov, V., Rehefeld, G., Wolm, G., Golovnja, R.V., and Roth, M. 1976. Volatile sulfur components contributing to meat flavor. 1. Components identified in boiled meat. Nahrung 20:235. Giacino, C. 1970. Meat flavoring based on taurine and thiamine. US Patent 2 519 437. Golovnja, R.V. and Rothe, M. 1980. Sulfur containing compounds in volatile constituents of boiled meat. Nahrung 24:141. Goosens, A.E. 1974. Protein foods - Its flavors and off flavors. Flavor Ind. 5:273. Greenberg, M.J. 1981. Characterization of poultry byproduct meat flavor volatiles. J. Agric. Food Chem. 29:831. Gremli, H.A. 1974. Interactions of flavor compounds with soy protein. J. Am. Oil Chem. Soc. 51:95A. Greuell, E.H. 1974. Some aspects of research in the applications of soy proteins in foods. J. Am. Oil Chem. Soc. 51:98A. Grey, T.C. and Shrimpton, O.H. 1967. Volatile components in the breast muscle of chicken of different ages. Br. Poult. Sci. 8:35. Gutcho, M. (Ed.). 1973. ”Textured Foods and Allied Products." Noyes Data Corp., Park Ridge, NJ. Gutcho, M. (Ed.). 1977. ”Textured Protein Products." Noyes Data Corp., Park Ridge, NJ. Hashida, W. 1974. Flavor potentiation in meat analogs. Food Trade Rev. 44(1):21. Hartman, G.J., Carlin, J.T., Hwang, S.S., Bao, Y., Tang, J., and Ho, C.-T. 1984. Identification of 3,5-diisobutyl- 1,2,4-trithiolane and 2-isobutyl-3,5-diisopropylpyridine in fried chicken flavor. J. Food Agric. Sci. 49:1398. Heath, H.B. 1972. Flavor in novel foods. Food Manufacture 47(1):21. 86 Heinze, R.F., Ingle, M.B., Reynolds, J.F. 1978. Flavoring vegetable protein meat analogs. In "Flavor of Foods and Beverages, Chemistry and Technology," G. Charalambous and G.E. Inglett (Ed.), p. 43. Academic Press, NY. Herz, K.O. 1968. A study of the nature of boiled beef flavor. Ph.D. dissertation, Rutgers State Univ., New Brunswick, NJ. Herz, K.0. and Chang, S.S. 1970. Meat flavor. Adv. Food Res. 18:1. Hicks, K.B., Harris, D.W., Feather, M.S., and Leoppky, R.N. 1974. Production of 4-hydroxy-5-methyl-3(2H)-furanone, a compound of beef flavor, from l-amino-1-deoxy-D-fructuronic acid. J. Agric. Food Chem. 22:724. Hicks, K.B. and Feather, M.S. 1975. Studies on the mechanism of formation of 4-hydroxy-5-methyl-3(2H)-furanone, a component of beef flavor from Amadori products. J. Agric. Food Chem. 23:957. Hirai, C., Herz, K.O., Pokerny, J. and Chang, S.S. 1973. Isolation and identification of volatile flavor compounds in boiled beef. J. Food Sci. 38:393. Ho, C.-T., Lee, K., and Jin, 0.2. 1983. Isolation and identification of volatile flavor compounds in fried bacon. J. Agric. Food Chem. 31:336. Hodge, J.E. 1953. Dehydrated foods. Chemistry of browning reactions in model systems. J. Agric. Food Chem. 1:928. Hodge, J.E. 1967. Origin of flavor in foods - Nonenzymatic browning reactions. In "The Chemistry and Physiology of Flavors," H.W. Schultz, E.A. Day, and L.M. Libbey (Ed.), p. 465. AVI Publishing Co., Westport, CT. Hoffman, G. and Meijboom, P.W. 1968. Isolation of two isomeric 2,6- nonadienal and two isomeric 4-heptenal from beef and mutton tallow. J. Am. Oil Chem. Soc. 45:468. Holley, R.A. 1978. Review of the potential hazards from botulism in cured meats. Can. Inst. Food Sci. Tech. J. 14:185. Honig, O.H., Rackis, J.J., and Sessa, D.J. 1971. Isolation of ethyl-2- d-galactopyranoside and pinitol from hexane-ethanol extracted soybean flakes. J. Agric. Food Chem. 19:543. Hornstein, I. and Crowe, P.F. 1960. Flavor studies on beef and pork. J. Agric. Food Chem. 8:494. Hornstein, K. and Teranishi, R. 1967. The chemistry of flavor. Chem. Eng. News 45(15):92. 87 Hornstein, K., Crowe, P.F., and Sulzbacher, W.L. 1960. Constituents of meat flavor: beef. J. Agric. Food Chem. 8:65. Hrdlicka, J. and Cuba, P. 1971. Study of change in course of thermal and hydrothermal processes. XV. Determination of sulphydryl groups produced by heating soybean protein with glucose. Sborn. Vysoke Skoly Chem.-Tech. V Praze, E, 30:31. Hsieh, Y.P.C., Pearson, A.M., and Magee, W.T. 1980. Development of a synthetic meat flavor mixture by using surface response methodology. J. Food Sci. 45:1125. Hsieh, Y.P.C., Pearson, A.M., Sweeley, C.C., and Martin, F.E. 1981. Use of spectral search for identification of volatiles in a synthetic meat flavor system. J. Food Sci. 45:1078. Hsu, C.M, Peterson, R.J., Jin, 0.2., Ho, C.-T., and Chang, S.S. 1982. Characterization of new volatile compounds in the neutral fraction of roasted beef flavor. J. Food Sci. 47:2068. Jassmann, E. and Schultz, H. 1963. Ringschlubreakionen in der ephedrinreihe, II. Synthese neuer 3-oxazolne. Pharmazie 18:527. Kalbrenner, J.E., Eldridge, A.C., Moser, H.A., and Wolf, W.J. 1971. Sensory evaluation of commercial soy flours, concentrates and isolates. Cereal Chem. 48:595. Kato, S.T., Kurata, T., and Fujimaki, M. 1973. Volatile compounds produced by the reactions of L-cysteine or L-cystine with carbonyl compounds. Agric. Biol. Chem. 37:539. Kato, Y., Watanabe, K., and Sato, Y. 1981. Effects of some metals on the Maillard reaction of ovalbumin. J. Agric. Food Chem. 29:540. Kinsella, J.E. 1969. Possible involvement of hydrogen ions in the chemical reaction of sulfur in flavor. Chem. Ind. p. 1654. Kinsella, J.E. 1983. Protein texturization, fabrication and flavoring. CRC Handbook of Nutritional Supplements 1:35. Kinsella, J.E. and Damodaran, S. 1980. Flavor problems in soy proteins: Origin, nature, control and binding phenomena. In "The Analysis and Control of Less Desirable Flavors in Foods and Beverages," G. Charalambous (Ed.), p. 95. Academic Press, NY. Kinsella, J.E., Damodaran, S., and German, 8. 1985. Physical chemical and functional properties of oilseed proteins with emphasis on soy proteins. In "New Protein Food, Vol. 5,“ A.M. Altschul and H.L. Wilcke. (Eds.), Acad. Press Inc., NY. Kleipool, R.J.C. and Tas, A.C. 1973. Product of Maillard reaction. I. 2-(2-Furyl)-thiazole. Riech. Arom. Koer. 23:326. 88 Kleipool, F.J.C. and Tas, A.C. 1974. Methylsubstituted allyl- and propenyl pyrazines. Riech. Arom. Koer. 24:326. Kobayashi, N., and Fujimaki, M. 1965. On the formation of N-acetyl- pyrrole on roasting hydroxypyroline with carbonyl compound. Agric. Biol. Chem. 29:1059. Koehler, P.E. and Odell, G.V. 1970. Factors affecting the formation of pyrazine compounds in sugar-amine reactions. J. Agric. Food Chem. 18:895. Koehler, P.E., Mason, M.E., and Newell, J.A. 1969. Formation of pyrazine compound in sugar-amino acid model systems. J. Agric. Food Chem. 17:393. Kotula, A.W. and Berry, B.W. 1986. Addition of soy proteins to meat products. In "Applications, Biological Effects and Chemistry," Ory, R.L. (Ed.), p. 74. American Chemical Society, Washington, DC. Kramlich, W.E. and Pearson, A.M. 1960. Separation and identification of cooked beef flavor components. Food Res. 25:712. Kuramoto, S. and Katz, 1. 1975. Flavoring fabricated foods. In "Fabricated Foods," G. Inglett, (Ed.), p. 159. AVI Publishing, Westport, CT. Langsdorf, A.J. 1981. Economics of soya protein products and outlook. J. Am. Oil Chem. Soc. 58:338. Lawrie, R.A. 1982. The flavor of meat and meat analogues. Food, p. 11. Ledl, F. and Severin, T. 1972. Thermal decomposition of cysteine in tributyrin. Chem. Mikrobiol. Tech. Lebensm. 1:135. Ledl, F. and Severin, T. 1973. Thermal decomposition of cysteine and xylose in tributyrin. Chem. Mikrobiol. Tech. Lebensm. 2:155. Ledl, F. and Severin, T. 1974. Sulfur-containing compounds from cysteine and xylose. Z. Lebensm. Unters. Forsch 154:29. Lee, T.-C., Pintauro, S.J., and Chickester, C.O. 1981. Physiological and safety aspects of Maillard browning of foods. Prog. Food Nutr. Sci. 5:24. Liebich, H.M., Douglas, D.R., Ziotkis, A., Miggar-Chjavan, F., and Donzel, A. 1972. Volatile components in roast beef. J. Agric. Food Chem. 20:96. Lillard, D.A. and Ayres, J.C. 1969. Flavor compounds in country cured hams. Food Tech. 23:251. Lyon, B.G. 1980. Sensory profiling of canned boned chicken: sensory evaluation procedures and data analysis. J. Food Sci. 45:1341. 89 MacLeod, G. and Ames, J.M. 1986. Capillary gas chromatography-mass spectrometric analysis of cooked ground beef aroma. J. Food Sci. 51:1427. MacLeod, G. and Coppock, B.M. 1976. Volatile flavor components of beef boiled conventionally and by microwave radiation. J. Agric. Food Chem. 24:835. MacLeod, G. and Coppock, B.M. 1977. A comparison of the chemical composition of boiled and roasted aromas of heated beef. J. Agric. Food Chem. 25:113. MacLeod, G. and Seyyedain-Ardebili, M. 1981. Natural and simulated meat flavor. CRC Rev. Food Sci. Nutr. 14:309. Maga, J.A. 1973. A Review of flavor, investigations associated with the soy products, raw soybeans, defatted flakes and flours and isolates. J. Agric. Food Chem. 21:864. Maga, J.A. 1978. Oxazoles and oxazolines in foods. J. Agric. Food Chem. 26:1049. Maillard, L.C. 1912. Action des acids amines dur les sucres: Formation des milanoidines par vois methodique. Compt. Red. 154:66. Manley, C.H. and Fagerson, 1.3. 1970. Major volatile compounds of hydrolyzed soy proteins. J. Food Sci. 35:286. Manson, M.E. and Katz, I. 1976. Role of flavor in new protein tech- nologies. In "New Protein Foods," Vol. 2, A. Altschul (Ed.), p. 122. Academic Press, New York. Mattick, L.R. and Hand, 0.8. 1969. Identification of a volatile component in soybean that contributes to the raw bean flavor. J. Agric. Food Chem. 17:15. May, C.G. 1974. An introduction to synthetic meat flavor. Food Trade Rev. 44(1):7. Merritt, C.J., Angelini, P., Wierbicki, E., and Schults, G.W. 1974. Chemical changes associated with flavor in irradiated meat and fish. Abstr. of Papers No. 168, American Chemical Society, Washington, DC. Mills, F.D., Baker, B.G., and Hodge, J.E. 1969. Amadori compounds as nonvolatile flavor precursors in processed foods. J. Agric. Food Chem. 17:723. Mills, F.D., Weisleder, D., and Hodge, J.F. 1970. 2,3-Dihydro-3,5- dihydroxy-6-methyl-4H-pyran-4-one, a novel nonenzymatic browning product. Tetrahedron Lett. p. 1243. 9O Mills, F.D. and Hodge, J.E. 1976. Amadori compounds: Vacuum thermo- lysis of 1-deoxy-1-L-proline-D-fructose. Carbohydr. Res. 51:9. Min, D.B.S., Peterson, R.J., and Chang, S.S. 1979. Preliminary identification of volatile flavor compounds in the neutral fraction of roast beef. J. Food Sci. 44:639. Morrisson, R.T. and Boyd, R.N. (Eds.). 1976. "Organic Chemistry," Allyn and Bacon, Inc., Boston, MA. Mottram, D.S., Edwards, R., and Macfie, J. 1982. A comparison of flavor volatiles from cooked beef and pork meat systems. J. Food Sci. Agric. 33:934. Mulders, E.J. 1973. Volatile components from the nonenzymatic browning reaction of cysteine-cystine-ribose system. Z. Lebensm. Unters. Forsch 152:193. Mussinan, C.J., and Katz, 1. 1973. Isolation and identification of some sulfur chemicals present in two model systems approximating cooked meat. J. Agric. Food Chem. 21:43. Mussinan, C.J. and Walradt, J.P. 1974. Constituents of pressure cooked pork liver. J. Agric. Food Chem. 22:827. Mussinan, C.J., Wilson, R.A., and Katz, 1. 1973. Isolation and identification of pyrazines present in pressure cooked beef. J. Agric. Food Chem. 21:871. Mussinan, C.J., Wilson, R.A., Katz, 1., Kruza, A., and Vock, M.H. 1976. Identification and flavor properties of some 3-oxazolines and 3-thiazolines isolated from cooked beef. In "Phenolic, Sulfur, and Nitrogen Compounds in Food Flavors," G. Charalambous and I. Katz (Ed.), p. 133. ACS Symp. Series No. 26. American Chemical Society, Washington, DC. Nonaka, M., Black, D.R., and Pippen, E.C. 1967. Gas chromatographic and mass spectral analysis of chicken meat volatiles. J. Agric. Food Chem. 15:713. Newell, J.A., Mason, M.E., and Matlock, R.S. 1967. Precursors of typical and atypical roasted peanut flavor. 1967. J. Agric. Food Chem. 15:767. Nixon, L.N., Wong, E., Johnson, 0.8., and Birch, E.J. 1979. ‘Non- acidic constituents of volatiles from cooked mutton. J. Agric. Food Chem. 27:355. Noller, C.R. (Ed.). 1966. "Chemistry of Organic Compounds,” W.B. Saunders Co., New York. Nursten, H.E. 1980. Recent developments in studies of the Maillard reaction. Food Chem. 6:263. 91 Ohloff, G. and Flament, I.. 1978a. New developments in meat aroma research. In "Flavors of Foods and Beverages, Chemistry and Technology," G. Charalambous and G.E. Inglett (Eds.), p. 15. Academic Press, New York. Ohloff, G. and Flament, I. 1978b. Heterocyclic constituents of meat aroma. Heterocycles 11:663. Pagington,.J.S. 1975. Flavoring and production of extruded soy protein. Inter. Flavors and Food Add. 6:278. Palkert, P.E. 1980. The determination Of flavor retention and native volatiles in rare-extrusion flavored textured soy protein. Ph.D. dissertation, Univ. of Massachusetts, Amherst, MA. Persson, T. and von Sydow, E. 1974. The aroma of canned beef: Application of regression models relating sensory and chemical data. J. Food Sci. 39:537. Persson, T. and von Sydow, E. 1973. Aroma of canned beef: Gas chromatographic and mass spectrometric analysis of the volatiles. J. Food Sci. 38:377. Peterson, R.J. and Chang, S.S. 1982. Identification of volatile flavor compounds of fresh, frozen beef stew and a comparison of these with those of canned beef stew. J. Food Sci. 47:1444. Peterson, R.J., Izzo, H.J., Jungermann, E., and Chang, S.S. 1975. Changes in volatile flavor compounds during the retorting of canned beef stew. J. Food Sci. 40:948. Piotrowski, E.G., Zaika, L.L., and Wasserman, A.E. 1970. Studies on aroma of cured ham. J. Food Sci. 35:321. Pittet, A.O. and Hruza, D.E. 1974. Comparative study of flavor properties of thiazole derivatives. J. Agric. Food Chem. 22:264. Qvist, I.H. and von Sydow, E. 1974. Unconventional proteins as aroma precursors, chemical analysis of volatile compounds in heated soy casein, and fish protein model systems. J. Agric. Food Chem. 22: 1077. Qvist, I.H., von Sydow, E., and Akesson, C.A. 1976. Unconventional proteins as aroma precursors: Instrumental and sensory analysis of the volatile compounds in a canned meat product containing soy or rapeseed protein. Lebensm. Wiss. Tech. 9:311. Rackis, J., Honig, O.H., Sessa, D.J., and Moser, H.A. 1972. Lipoxy- genase and peroxide activities of soybeans as related to the flavor profile during maturation. Cereal Chenh 49:586. 92 Rackis, J., Sessa, 0., and Honig, D.J. 1979. Flavor problems of vegetable food proteins. J. Am. Oil Chem. Soc. 56:262. Rakosky, J. 1974. Soy grits, flour, concentrates and isolates in meat products. J. Am. Oil Chem. Soc. 51:123A. Reineccius, G.A., Keoney, P.G., and Weissberger, W. 1972. Factors affecting the concentration of pyrazines in cocoa beans. J. Agric. Food Chem. 20:202. Ritter, W.J. 1978. Flavoring systems for meat analogs and extenders. Food Prod. Develop. 12:60. Rizzi, G.P. 1969. Formation of tetramethylpyrazine and 2-isoprOpyl- 4,5-dimethyl-3-oxazoline in the Strecker degradation of DL-valine with 2,3-butanedione. J. Org. Chem. 34:2002. Rizzi, G.P. 1972. A mechanistic study of alkylpyrazine formation in model systems. J. Agric. Food Chem. 20:1081. Roberts, D.L. 1964. Process of imparting a popcorn-like flavor and aroma to foodstuffs and tobacco by incorporating pyrazine derivatives therein and the resulting product. US. Patent 3 402 051. Sanderson, A., Pearson, A.M., and Schweigert, 8.5. 1966. Effect of cooking procedure on flavor components of beef carbonyl compounds. J. Agric. Food Chem. 14:245. Scanlan, R.A., Kayser, S.G., Libbey, L.M., and Morgan, M.E. 1973. Identification of volatile compounds from heated L-cysteine.HCL/D- glucose. J. Agric. Food Chem. 21:673. Schutte, L. 1976. Flavor precursors in food stuffs. In "Phenolic, Sulfur, and Nitrogen Compounds in Food Flavors," G. Charalambous and O. Katz (Ed.). ACS Symp. Series No. 26:133. American Chemical Society, Washington, DC. Schutte, L. 1974. Precursors of sulfur containing flavor compounds. CRC Crit. Rev. Food Sci. Nutr. 7:457. Schutte, L. and Koenders, E.B. 1972. Components contributing to beef flavor, natural precursors of l-methylthioethanethiol. J. Agric. Food Chem. 20:181. Schutte, L. and van den Ouweland, G.A.M. 1979. Flavor problems in the application of soy protein materials. J. Am. Oil Chem. Soc. 56:289. Schrodter, R. and Wolm, G. 1980. Studies on optimal conditions for flavor formation in amino acid-glucose model systems. Nahrung 24: 175. 93 Self, R., Casey, J.C., and Swain, T. 1963. The low boiling volatiles of cooked food. Chem. Ind. (London), p. 863. Sessa, D.J., Honig, O.H., and Rackis, J.J. 1969. Lipid oxidation in full-fat and defatted soybean flakes as related to soybean flavor. Cereal Chem. 46:675. Sessa, D.J., Gardner, H.W., Kleiman, R., and Weisleder, D. 1977. Oxygenated fatty acid constituents of soybean phosphatidylcholines. Lipids 12:613. Sessa, D.J., and Rackis, J.J. 1979. Lipid-derived flavors of legume protein products. J. Am. Oil Chem. Soc. 56:468. Sessa, D.J., Warner, K., and Honig, O.H. 1974. Soybean phosphatidyl- choline develops bitter taste on autoxidation. J. Food Sci. 39:69. Sessa, D.J., Warner, K., and Rackis, J.J. 1976. Oxidized phosphatidyl- choline from defatted soybean flakes taste bitter. J. Agric. Food Chem. 24:16. Shahidi, F., Rubin, L.J., and D'Souza, L.A. 1986. Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation. CRC Crit. Rev. Food Sci. Nutr. 24:141. Shankaranarayana, M.L., Raghaven, 8., Abraham, K.O., and Natarajan, C.P. 1982. Sulfur compounds contributing to meat flavor. 1. Components identified in boiled meat. Nahrung 20:235. Shibamoto, T. and Bernhard, R.A. 1977a. Investigation of pyrazine formation pathways in sugar-ammonia model systems. J. Agr. Food Chem. 25:609. Shibamoto, T. and Bernhard, R.A. 1977b. Investigation of pyrazine formation pathways in glucose-ammonia model systems. Agric. Biol. Chem. 41:143. Shibamoto, T., and Russell, G.F. 1976. Study of meat volatiles associated with aroma generated in a D-glucose-hydrogen sulfide- ammonia model system. J. Agric. Food Chem. 24:843. Shigematsu, H., Shibata, 5., Kurata, T., Kato, H., and Fujimaki, M. 1975. 5-Acetyl-2,3-dihydro-1H-pyrrolizines and 5,6,7,8-tetrahydro- indilizin-8-ones, the constituents formed on heating L-proline with D-glucose. J. Agric. Food Chem. 23:233. Shu, C.K., Hagedorn, M.L., and Ho, C.-T. 1986. Two novel thiophenes identified from reaction between cysteine and 2,5-dimethyl-4- hydroxy-3(2H)-furanone. J. Agric. Food Chem. 34:344. Stoll, M., Dietrich, P., Sundt, E., and Winter, M. 1967a. Sur l'arome du cocoa II. Helv. Chim. Acta. 50:2065. 94 Stoll, M., Dietrich, P., Sundt, E., and Winter, M. 1967b. Sur l'arome du cafe'. Helv. Chim. Acta. 50:627. Schweiger, R.G. 1974. Protein concentrates and isolates in comminuted meat systems. J. Am. Oil Chem. Soc. 51:192A. Takken, H.H., van der Linde, L.M., de Valois, P.J., van Dort, H.M., and Boelens, M. 1976. Reaction products of dicarbonyl compounds, aldehydes, hydrogen sulfide and ammonia. In "Phenolic, Sulfur and Nitrogen Compounds in Food Flavor.". G. Charalambous and O. Katz (Eds.), ACS Symp. Series No. 26, 114. American Chemical Society, Washington, DC. Tonsbeek, C.H.T., Copier, H., and Plancken, A.J. 1971. Components contributing to beef flavor: Isolation of 2-acetyl-2-thiazoline from beef broth. J. Agric. Food Chem. 19:1014. Tonsbeek, C.H.T., Plancken, A.J., and Weerhof, T. 1968. Components contributing to beef flavor: Isolation of 4-hydroxy-5-methyl-3- (2H)-furanone and its 2,5-dimethyl homolog from beef broth. J. Agric. Food Chem. 16:1016. Tressl, R. 1979. Formation of aroma substances by means of the Maillard reaction. Monatsch. Brau. 32:240. Tressl, R., Renner, R., Kossa, T., Koepler, H. 1977. Gas chromato- graphic-mass spectrometric investigation of volatile components of hOps, warts, and beer and their formation. III. Nitrogen-containing aroma compounds in malt and beer. Proc. European Brew. Convention, 16th Congress, p. 693. Tressl, R. and Silwar, R. 1981. Investigation of sulfur-containing components in roasted coffee. J. Agric. Food Chem. 29:1078. Uralets, V.P. and Golovnja, R.V. 1980. Monocarbonyl compounds in boiled beef flavor. Comparison of standardless gas chromatographic identification and combined gas chromatographic spectrometry. Nahrung 24:155. van den Ouweland, G.A.M., Olsman, H., and Peer, H.G. 1978. Challenges in meat flavor research. In "A ricultural and Food Chemistry: Past, Present, Future,: R. Teranishi IEd.), p. 292. AVI Publishing Co., Westport, CT. van den Ouweland, G.A.M. and Peer, H.G. 1975. Components contributing to beef flavor volatile compounds produced by the reaction of 4-hydroxy-5-methyl-3(2H)-furanone and its thio analog with hydrogen sulfide. J. Agric. Food Chem. 23:501. van den Ouweland, G.A.M. and Peer, H.G. 1978. Occurrence of amadori and heyns rearrangement products in processed foods and their role in flavor formation. In "Flavor of Foods and Beverages, Chemistry and Technology," G. Charalambous and G.E. Inglett (Ed.), p. 131. Academic Press, New York. 95 van den Ouweland, G.A.M. and Schutte, L. 1978. Flavor problems in the application of soy protein materials as meat substitutes. In "Flavors of Foods and Beverages, Chemistry and Technology," G. Charalambous and G.E. Inglett (Eds.), p. 34. Academic Press, New York. van Praag, M., Stein, H.S., and Ribbetts, M.S. 1968. Steam volatile aroma constituents of roasted cocoa bean. J. Agric. Food Chem. 16:1005. Vercellotti, J.R., St. Angelo, A.J., Legendre, M.G., Vinnett, C.H., Kuan, J.W., James, C.J., and Dupuy, H.P. 1987. Chemical and instrumental analysis of warmed-over flavor in beef. J. Food Sci. 52:1163. Wainwright, T., McMahon, J.F., and McDowell, J. 1972. Formation of methional and methanethiol from methionine. J. Sci. Food Agric. 23:911. Wang, P. and Odell, G.V. 1973. Formation of pyrazines from thermal treatment of some amino-hydroxyl compounds. J. Agric. Food Chem. 21:868. Wasserman, A.E. and Spinelli, A.M. 1970. Sugar-amino acid interactions in the diffusate of water extract of beef and model systems. J. Food Sci. 35:328. Wasserman, A.E. 1979. Symposium on meat flavor. Chemical basis for meat flavor - A review. J. Food Sci. 44:6. Watanabe, K. and Sato, Y. 1968a. AliphaticT-and o-lactones in meat fats. Agric. Biol. Chem. 32:1318. Watanabe, K. and Sato, Y. 1968b. Studies on the changes of meat fats by various processing. 11. Gas chromatographic identification of aliphatic - and - lactones obtained from beef fats. Agric. Biol. Chem. 32:191. Watanabe, K. and Sato, Y. 1971a. Gas chromatographic and mass spectral analysis of heated flavor compounds of beef fats. Agric. Biol. Chem. 35:756. Watanabe, K. and Sato, Y. 1971b. Some alkyl-substituted pyrazines and pyridines in the flavor components of shallow fried beef. J. Agric. Food Chem. 19:1017. Watanabe, K. and Sato, Y. 1972. Shallow fried beef: Additional flavor components. J. Agric. Food Chem. 20:174. Wicks, E.L. 1963. Volatile components of irradiated beef. In "Exploration in Future Food Processing Techniques," S.A. Goldblith (Ed.), p. 5. MIT Press, Cambridge, MA. 96 Wicks, E.L. 1965. Chemical and sensory aspects of the identification of Odor constituents in foods: A review. Food Tech. 19:827. Wicks, E.L., Murray, E., Mizutani, J., and Koshika, M. 1967. Radiation in preservation of foods. ACS Symp. Series No. 65. American Chemical Society, Washington, DC. Wilkens, W.F. and Lin, F.M. 1970a. Gas chromatographic and mass spectral analysis of soybean milk volatiles. J. Agric. Food Chem. 18:333. Wilkens, W.F. and Lin, F.M. 1970b. Volatile components of deep fat- fried soybeans. J. Agric. Food Chem. 18:337. Williams, M.A., Horn, R.E., and Rugala, R.P. 1977. Extrusion, Part 1. Food Eng. 46(9):99. Wilson, R.A. 1975. A review of thermally produced imitation meat flavors. J. Agric. Food Chem. 23:1032. Wilson, R.A. and Katz, I. 1972. Review of literature on chicken flavor and report of isolation of several new chicken flavor components from aqueous cooked chick broth. J. Agric. Food Chem. 20:741. Wilson, R.A., Mussinan, C.J., Katz, 1., and Sanderson, A. 1973. Isolation and identification of some sulfur chemicals present in pressure-cooked beef. J. Agric. Food Chem. 21:873. Wolf, W.J. 1970. Soybean proteins: Their functional chemical and physical properties. J. Agric. Food Chem. 18:969. Wolf, W.J. 1975. Lipoxygenase and flavor Of soybean protein products. J. Agric. Food Chem. 23:136. Wong, E., Nixon, L.N., and Johnson, C.B. 1975. Volatile medium-chain fatty acids and mutton flavor. J. Agric. Food Chem. 23:495. Yamaguchi, K., Shudo, K., Okamoto, T., Sugimura, T., and Kosuge, T. 1980. Presence of 3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole in broiled beef. Gann 71:745. Yamato, T., Kurata, T., Kato, H., and Fujimaki, M. 1970. Volatile carbonyl compounds from heated beef fat. Agric. Biol. Chem. 34:80. CHAPTER I COMPARATIVE AROMA ASSESSMENT OF SELECTED MEAT/BEEF FLAVORS ABSTRACT The meatiness and general aroma qualities of two synthetic meat flavors (HH and SW) thermally generated from mixtures Of meat flavor precursors were sensorially compared to those of the commercial (BV, MM, HO, and GG) and natural (BE) beef flavors. A sample from each group (HH, HO, and BE) was selected for further descriptive aroma evaluation against a conceptualized I“Ideal" meat flavor. The synthetic flavors were significantly more meaty than the commercial samples while not being significantly different in meatiness from the natural sample. The dominant aroma qualities of HH were "Meaty", ”Toasted/Burnt", and "Cooked Vegetables", of HO were "Spicy/Fragrant" and "Cooked Vegetables" and of BE were “Meaty" and "Flat/Dull". 97 O INTRODUCTION A synthetic meat flavor consisting of an autoclaved mixture of meat flavor precursors (amino acids, simple reducing sugars, 5'-nucleotides, and glycoprotein) and salt with fat as an optional component was developed by Hsieh et al. (1980). The thermally-generated meat flavor mixture was found to be equal or superior to several of the commercially available synthetic meat flavor mixtures and nearly equal to natural beef extract. Concurrently, a system involving a mixture of amino acids and glucose was independently developed in East Germany by Schrodter and Wolm (1980). However, descriptive sensory evaluations were not conducted on either models. Despite the importance of correlating chemical data with sensory scores for meat aroma, only four detailed descriptive sensory reports on meat aroma are available. The first was a study of the sensory properties of canned beef aroma using 28 odor qualities (Persson et al., 1973), while a second involved a comparison of the Odor qualities of beef cooked conventionally and by microwave radiation (MacLeod and COppock, 1978). More recently, Galt and MacLeod (1983) applied factor analysis to previously published data (MacLeod and Coppock, 1978) and concluded that nine major factors describe the sensory prOperties of raw/cooked (boiled and roasted) beef aroma. With regard to simulated meat flavors, MacLeod and Seyyedain-Ardebili (1981) published the only 98 99 report comparing the sensory properties of the aroma of natural (boiled and roasted) and some commercially available simulated beef flavors. However, the compositions of these simulated flavors were not disclosed. Because of our interest in meat flavor development via pre-extrusion addition of flavor precursors, the model conceived by Hsieh et al. (1980) and a model based on the composition proposed by Schrodter and Wolm (1980) were first evaluated sensorially for their meatiness and aroma qualities, and compared with those of commercial and natural beef flavors. On the basis of this study, three samples each of synthetic, commercial, and natural origins were selected for further descriptive aroma evaluations. The purpose of this study was to relate the develop- ment of meat flavor to formulation variables in a systematic manner. The flavor precursor mix of the selected model was used in subsequent extrusion studies. EXPERIMENTAL Selection of Meat/Beef Flavors Two synthetic, four commercial and one natural meat/beef flavor mixtures were selected for this study and their compositions are presented in Table 1. Synthetic meat flavors were thermally generated from a mixture of flavor precursors and could be consistently and easily reproduced in the laboratory. Of the commercial samples, only those described as beefy flavored, Offered variety with respect to price and composition, and that were available in local supermarkets/ specialty shops, were selected for the study. Based on earlier conclusive evidence that precursors of the characteristic aroma of meat are low molecular weight, water-soluble compounds (Batzer et al., 1960; 1962; Wasserman and Gray, 1965; Zaika et al., 1968), a heated cold-water extract of ground beef chuck was used as the natural beef (or reference) flavor sample. Preparation of Meat/Beef Flavors Synthetic Meat Flavors The synthetic meat flavor mixture developed by Hsieh et al. (1980) was prepared as described. A second system of the composition proposed by Schrodter and Wolm (1980) was also prepared. The chemical composition of these two systems is presented in Table 2. 100 Table 1. 101 flavors. Chemical compositions of flavor precursors of synthetic meat a Flavor precursors Synthetic meat flavors b HH Sim le 0 su ars Glucose g 60 (6.4)C 220.7 (23.6)C Ribose 40 (4.3) Xylose 60 (6.4) Subtotal 160 (17.1) 220.7 (23.6) L-amino acids Glycine 8 (0.8) 18.7 (2.0) Alanine 23 (2.5) 18.7 (2.0) Leucine 10 (1.0) Isoleucine 9 (1.0) Serine 21 (2.2) 18.7 (2.0) Cysteine Hydrochloride 20 (2.1) 63.6 (6.8) Methionine 11 (1.2) Taurine 22 (2.4) Aspartic acid 112.2 (12.0) Glutamic acid 239.4 (25.6) Glutamic acid (monosodium salt) 20 (2.1) Arginine 6 (0.6) 112.2 (12.0) Histidine 18.7 (2.0) Proline 112.2 (12.0) Subtotal 150 (15.9) 714.4 (76.4) 5'-Nucleotides Inosine monophosphate (IMP) 25 (2.7) Glycoprotgin Gelatin 500 (53.5) Salt Sodium chloride (Table salt) 100 (10.7) Total 935 (99.9) 935.1 (100.0) aAll chemicals were of 95-99%+ purity and obtained from Sigma Chemical Company (St. Louis, MO) except where specified. bSee Table 2. d cPercent dry weight. Weight in mg per 50 mL of deionized water. *Knox unflavored gelatin (Lipton Co., Englewood Cliffs, NJ). 102 eo.~\o.ma mumea \cwguwump cemaxom use .m:_eo>mpe .wmz .d>: mzoum_> .uew Coma .wmma umummoc mzpq :o_uepasgow uwmem :zocn xeeo eemmme ow omen azom umeo>epmimmmm co.0\m.~e\mmu_am use .comco .cwcuxmcioupes .gemzm .mcwco>mpy Poeaum: maze wuamm .uew Coma .uuecaxm moon mapa :o_umpzsgow uwmem :zoen “saw; emmmm: o: omen asom umeo>eprwmmm om.fi\m.fia\o_eoe=o eea ooep_am anoga+ xgv . um: .m>z .umw wows mnzu muzem .xuoum Coma emuecuxsmu mapm cowuepzscoe uwmem czoen unmwg zwmmme z: omen anew nmeo>e~CICmmm co.M\o.ma\moocam eea eeoe owooap eeea2_ .zucmum .uumcuxm ammo» .«¢>z .wmwn comp maoumw> vmcchOQ .:_muoeq Coma nmmxpoccxc .uuecuxm czoca use xooum Coma mspa cowuepaacom uwmem xeev .mzceqo ewmmme >m x:_gc umgo>e_wiwmmm u meo>e_m Coma Fe_ucmesou Aommfiv u_=cwp Epoz use Lmuvoezum an .umv.mfi\om.~\mmouzpm nae muwum zop_m> ummoqoca :o_u_moqaoo ocwEe Co mgzuxwa a sexy cmuecmcmm xppeEmee mFeq .eemFU exuemze 3m one :0 women Pmnoz mm.mm\um.fi\upem use .Acwumpmmv cwmuosaouxpm .w azmv muwuompuscI.m .meemzm acwoavmg mpaswm .m:_mpmxu .mcwcmm .mcwuzmpom_ .mcwuzmp .mcwcepe .mcwuzpmv mu_ue nwzc__ Aeomofiv .Fm um swam: ocmEe Co mcszwe e soc; umgmcmcmm >p_eELmzh czoca .Cewpu exumwzz I: xa umao_m>mu Pmuoz mco>mpw Home uwuwcucxm mucmcemaae Cm omen u mm: nam ooH\av mu_e¢\eAaV pm>mPImm:\mcowue_:scou _eu_mx;a waoeepd wmmm\uemz .mco>epe wmmn\umms Possum: use .Fewugmesou .u_um;ucxm Co mcowue_=scow use mmczuemw u_um_gmuuecenu .N mpnmh 103 mueEeuzpm E=wu_mo:oz um: :_m»oea mpamummm> om~>_oeuxz d>z muesqmosaocoe m:_mo:_ azH "meowaew>menne_w :o ummemu .mmu_ca umzmo—mpeu Aoz .mwaoA .am .xceanu Feu_Em;u mmsmwmv m.msm_m eo\ucm Pweumc pmoop acmecau seem umaeepammn .NooH x Lopez we a ooH Cog mco>epe wmmn\ueoe Co Amv segue om~.¢~\om.m2\xu:;u Coma uczocm comp Co space uuecuxm emue3IGFou Eoce cmuegmcmu apposemgh pews CemPu ewmmmz mm uuecuxw mama Peczuez co>mpm Coma Fecauez A.e.oeoov N o_eee 104 To develop the flavor in each of the synthetic systems, the components were weighed into a 125 mL flask and solubilized in 25 mL of deionized water. The mixture was then autoclaved at 17 psi for 90 min at 121°C (Castle Thermatic 60, Wilmot Castle Co., Rochester, NY). The flavor mixture was diluted with an equal volume of hot deionized water before presenting to the panel. Commercial Beef Flavors Four commercial beef flavors purchased from local supermarkets/ specialty shops were prepared according to the manufacturers' specifica- tions and standardized as follows: 10 g (:0.1 9) sample of the liquid/ paste or a sauce cube (3.75:0.1 g) was added to 200 mL (1 cup) of hot boiling water. Natural Beef Flavor Fresh ground beef chuck (80% lean) was obtained from Food Stores (Michigan State University, East Lansing, MI) and homogenized with 4 times its weight of cold deionized water for 2 min in a Waring blendor according to the procedure of Zaika et al. (1968). The homogenate was allowed to stand for 2 hr at 4°C and filtered through cheese cloth. The solids in the filtrate were further separated by centrifugation (International Centrifuge, Model K, size 2, top speed for 10 min; International Equipment Co., Needham Heights, MA). The supernatant, after discarding the top fat layer, was divided into 150 mL portions. Each portion was delivered into a 300 mL round- bottomed flask and subsequently frozen in a dry ice-acetone bath on a RotovaporR (model 310928, Buchi, Switzerland). The frozen portions 105 were lyOphilized overnight at room temperature (21°C). Approximately 37.1i1.3 g of freeze-dried extract was obtained from 1 kg of fresh ground beef chuck. The moisture content of the beef was found to be 66.8:O.3% (A.O.A.C. method 24.003, 1975). Based on this analysis, 1.45 g of the freeze—dried sample were redissolved in 25 mL of deionized water. For meat flavor development, the solution was autoclaved. Clear beef extract, served both as natural beef flavor and reference sample, was obtained by filtering the autoclaved sample through glass wool. Sufficient samples from each group were prepared a week in advance and stored under nitrogen at -20°C. Presentation of Meat/Beef Flavors Seven mL of each of the prepared meat/beef flavors were pipetted R vials and capped with hollow into 20 mL wide-necked Kimble Opticlear polyethylene caps (Thomas Scientific Co., Swedesboro, NJ). Each sample was randomly coded with a three-digit number, heated on high for 10 sec in a microwave oven (model 02216, Tappan Microwave Oven, Tappan Co., Mansfield, OH) and served immediately to the panelists in their individual booths. Three samples were served in a controlled order at each session. A reference sample of natural beef extract was provided throughout the first half of the study. The panelists were instructed to uncap the vials and to evaluate the aroma by sniffing in the order presented without retracking. TO eliminate any possible physical effects among samples, red-colored light was used during aroma assessment. 106 Experimental Designs and Sensory Methodology General Aroma Assessment The samples were initially presented in a balanced incomplete block design of seven treatments (treatments=blocks=7), number of replica- tions=number of treatments per block=3), number of occurrence per pair of treatments=1, and efficiency Of design=O.78; Cochran and Cox, 1957). All seven possible tertiary combinations of meat/beef flavors, were evaluated by each panelist over a total of seven sessions, with two sessions per day, for 3 1/2 consecutive days. At each session, the panelists were requested to: (a) evaluate each sample for "meaty" aroma on a 1 (does not contribute or resemble meat aroma) to 9 (excep- tionally good full meaty aroma) point scale as utilized by Hsieh et al. (1980), and (b) describe the perceived aroma qualities associated with each sample. Based on the results obtained, three samples each of synthetic, commercial, and natural origins were selected for further comparative study involving descriptive aroma evaluation. Descriptive Aroma Evaluation A completely randomized block design was used in the second half of this study. Only one session was conducted. The panelists were requested to score the three selected samples and a conceptualized ”Ideal" meat flavor for intensity of each of the six major aroma descriptors: "Meaty", "Cooked vegetables", "Toasted/Burnt", "Oily/ Fatty", "Spicy/Fragrant", and "Flat/Dull" on a 1-10 point scale where 1 represented none or absent and 10 represented very pronounced intensity. Ten-point intensity scales have previously been used by Persson et al. 107 (1973) and MacLeod and co-workers (1978; 1980). Sensory Panel Participating in this study were six trained panelists (2 females and 4 males, aged 20-40) recruited among the staff and graduate students at this research facility. They were previously screened from a pool of twenty-one panelists for their consistency in intensity scaling and ability to discriminate between aromas. All panelists have received formal training in sensory evaluation and were familiar with evaluating meat products. Statistical Analyses To ascertain whether significant differences exist and to afford multiple comparisons among samples, collected sensory data were statistically analyzed with Analysis Of Variance followed by Duncan's Multiple Range Test (Duncan, 1955) and/or Dunnett's t-test (Dunnett, 1964). The "Ideal" meat flavor was treated as the control in Dunnett's t-test for 1 control and 3 treatments. The applied statistical procedures and inferences were in accordance to those of Gacula and Singh (1984). RESULTS AND DISCUSSION General Aroma Assessment Preliminary evaluations of meaty aromas (Table 3) using 1 (does not contribute or resemble meat aroma) to 9 (exceptionally good full meaty aroma) revealed that the synthetic meat (HH and SW) and natural beef flavors (BE) were rated significantly higher than the four commercial beef flavors (BV, MM, HO and GG), while no significant difference was found between the natural and synthetic samples, or within sample groups at (p<0.01), as previously reported by Hsieh et al. (1980). The two synthetic meat flavor mixtures (HH and SW) were scored 5.8 and 5.6, respectively, indicating that they faintly (to slightly) resembled meat aroma. The commercial beef flavors (BV, MM, HO, and GG) had mean panel scores of 3.7, 3.4, 3.8, and 3.7, respectively, implying that they probably resembled meat aroma. The natural beef flavor (BE) had a slight meaty aroma and received a mean panel score of 6.1. The meatiness of the natural beef flavor (BE) could probably be increased by using a more concentrated extract. This may also have been true for the other flavors. Descriptive terms used by the panelists to evaluate the aroma qualities of the samples are summarized in Table 3. Many of the terms were previously used by Persson et al. (1973), and by MacLeod and Coppock (1978) to describe the cooked beef aroma. The synthetic meat 108 Table 3. 109 Meaty aroma ratings and general comments on aroma qualities of synthetic, commercial, and natural meat/beef flavors. Meat/Beef flavora Meaty aera ratings General comments on aroma qualities Synthetic meat flavord HH SW Commercial beef flavore BV MM HO GG Natural beef flavord BE 5.8:1.7 3.7:0.8 3.810.8 3.7i1.1 6.1t1.2 Burnt (14)°, sulfurous (10), onion-like (5), roasted meat (3), and vegetables (2) Strongly sulfurous (18), burnt (4), arlic-like (4), roasted meat I3), vegetables (2), onion-like (2), chemical-like (1) Cooked vegetables (10), onion- like (7), garlic-like (6), soy sauce like (4), spicy (3), sweet (3), bouillion-/oxo-/ MSG-like (1), and hydrolyzed vegetables (1) Strong vegetables (6), onion- like, burnt (6), bouillion- like (2), cooked potato-like (2), brothy (1), spicy (1), and SOy sauce-like (1) Onion-like (14), cooked vegetables (10), garlic-like (5), bouillion-like (2), soy sauce-like (2), salty (2), :weet (2), meaty (1), and burnt 1 Onion-like (14), vegetables (7), garlic-like (4), bouillion-like (4). sweet (4). spicy (3). brothy (2), salty (2), soy-like (1), and caramel (1) Sweet (8), boiled meat/diluted beef broth (5) a b See Table 2, and Experimental section for details. Means:standard deviations of a 6-member panel. A 1 (does not contribute or resemble meat aroma) to 9 (exceptionally good full 110 Table 3 (cont'd.) meaty aroma) point scale was used. CTotal frequency of use. dAre significantly higher than e at p<0.01 as established using the Analysis of Variance and Duncan's Multiple Range Test. 111 flavors were frequently described as sulfurous, burnt, and roasted meat, while cooked vegetables, garlic-like, and onion-like characterized the aromas of the commercial beef flavors. As Observed by MacLeod and Seyyedain-Ardebili (1981), burnt or roasted aroma qualities in the synthetic flavors tended to obliterate rather than augment the meaty aroma quality present. Sulfurous aroma, due to the addition of sulfur-containing amino acid(s) in the systems (Gutcho, 1977; MacLeod and Seyyedain-Ardibili, 1981; Hsieh et al., 1980), was more pronounced in SW than in HH. The major sulfur-donor(s) in SW and HH were cysteine hydrochloride and cysteine hydrochloride and methionine, respectively. Suppression of the sulfurous aroma could be brought about by (a) the addition Of gelatin and fat, and optimizing the ratio of cysteinezalanine as reported by Hsieh et al. (1980), (b) the addition of disodium inosinate (Kuninaki, 1966), and (c) adjusting the pH to 3.0 with sulfuric or hydrochloric acid to dispel excess hydrogen sulfide (Weiner, 1972). Interestingly, the aromas of the synthetic meat flavors were occasionally described as onion—like or garlic-like. Some of the non-enzymatic browning reaction products, viz., hydrocarbons, lactones, mercaptans, thiazolines, thiophenes, and disulfides, reportedly contribute to onion-like and/or garlic-like aroma qualities (Shahidi et al., 1986). These compounds may be present in the aroma volatiles of the synthetic flavors and contribute an onion-like or garlic-like note to their aroma. The aroma of the natural beef flavor was frequently described as sweet, boiled meat, and brothy. Batzer et al. (1960) similarly described the dialyzable water-extract of raw beef muscle as having a 112 beef broth aroma when boiled with water. The highest rated samples (HH of the synthetic meat flavors and H0 of the commercial beef flavors) were selected for subsequent extrusion studies. Comparative descriptive aroma evaluations were subsequently conducted on these flavor mixtures as well as the natural beef flavor (BE). Descriptive Aroma Evaluation The intensity scores of the six major descriptors for the selected and "Ideal" meat/beef flavors were statistically analyzed and are presented in Table 4. Selection Of the descriptors was based on comments resulting from general aroma assessments and from the work by Galt and MacLeod (1983). The results were in agreement with the preliminary findings of the previous section. Again, the synthetic meat flavor (HH) and the natural beef flavor (BE) were scored significantly (p<0.01) higher in "Meaty" aroma than the commercial beef flavor (HO), while no significant (p<0.0I) difference in meatiness was found between the synthetic (HH) and natural (BE) samples. The results of the descriptive aroma evaluations further indicated that the synthetic meat flavor (HH) was significantly (p<0.01) more pronounced in the "Toasted/Burnt" aroma qualities than the commercial (HO) and natural (BE) samples. On the other hand, the commercial beef flavor (HO) was significantly (p<0.01) more "Spicy/ Fragrant" than the other two samples (HH and BE). Interestingly, both the synthetic (HH) and commercial (HO) samples were scored higher in “Cooked Vegetables" than the natural (BE) sample at p<0.01, while the 113 Table 4. Intensity scores of six major aroma descriptors for an ”Ideal" and three selected meat/beef flavors. Major aroma Selected meat/beef flavorsa descriptor "Ideal" aroma qualities meat flavor Natural Synthetic Commercial (35) (HH) (H0) "Meaty“ 7.8:1.2° 6.2:1.2 6.0:1.2 3.3:O.5* meaty/boiled BE HH > HOc (p<0.01) meaty/roasted "Cooked vegetables" 4.3:1.0 2.7:1.2* 5.0:1.5 6.2:1.3* cooked cabbage vegetables, HO HH > BE (p<0.01) overcooked "Toasted/Burnt" 3.0:O.6 1.8:O.8 6.2:1.6** 3.5:1.4 toasted burnt HH > HO BE (p<0.01) "Oily/Fatty” 3.7:1.2 2.3:1.2* 2.0:O.9* 2.5:1.0 oily fatty HO BE HH (p<0.05) "Spicy/Fragrant" 4.7:1.5 3.7:1.6 3.8:1.7 6.5:1.2** spicy fragrant HO > HH BE (p<0.01) "Flat/Dull" 1.0:0.0 4.0:1.6** 1.7:O.8 2.0:1.07 flat dull BE > HO HH (p<0.05) a See Table 2 and Experimental section for details. Intensity scores were rated on a 1 (none) 10 (pronounced) point intensity scale. Values reported were the means:standard deviations of a 6-member panel. CSamples are listed in decreasing order of intensity where underscored samples are not significantly different as established using the Analysis of Variance and Duncan's Multiple Range Test. dLevel of significance. *and ** refers respectively to significantly lower and higher than "Ideal" at p<0.05 as established using the Analysis of Variance and Dunnett's t-test. b 114 latter was significantly (p<0.05) higher in ”Flat/Dull". In general, the dominant aroma properties (average intensity scores) associated with (a) the synthetic meat flavor (HH) were "Meaty" (6.0), "Toasted/Burnt" (6.2), and "CoOked Vegetables" (5.0), (b) the commercial beef flavor (HO) were "Spicy/Fragrant" (6.5), and "Cooked Vegetables" (6.2), and (c) the natural beef flavor (BE) were "Meaty" (6.2) and ”Flat/Dull" (4.0). All three samples (HH, HO, and BE) were described as having very slight "Oily/Fatty" aroma notes. Similar conclusions were drawn when comparing the selected meat/beef flavors against the "Ideal" meat flavor. At p<0.05, the synthetic meat flavor (HH) was significantly higher in "Toasted/Burnt" and lower in "Oily/Fatty" than ideally desirable, while the commercial beef flavor (HO) was significantly lower in "Meaty" and higher in "Spicy/Fragrant“ and "Cooked Vegetables" than the "Ideal" model. In contrast, the natural beef flavor (BE) was significantly (p<0.05) lower in "Cooked Vegetables" and "Oily/Fatty" and more pronounced in "Flat/Dull" than the "Ideal" meat flavor. "Flat/Dull" may be negatively correlated with "Meaty", "Toasted/Burnt", "Spicy/Fragrant“, and/or "Cooked Vegetable". The mean intensity scores of the six major aroma descriptors for the "Ideal" meat flavor were as follows: "Meaty" - 7.8, "Cooked Vegetables” - 4.3, "Toasted/Burnt" - 3.0, "Oily/Fatty" - 3.7, "Spicy/Fragrant" - 4.7, and "Flat/Dull" - 1.0. These scores may be viewed as the optimum or ideal levels of intensities. Again, some of the non-enzymatic reaction products, Strecker aldehydes, pyrazines, thiazoles, thiazoline, thiophenes, sulfides, and furans, have been reported to contribute to burnt and roasted aroma 115 qualities (Shahidi et al., 1986), and may be responsible for the more intense level of "Toasted/Burnt" aroma property in the synthetic flavor. However, aromatizing agents such as straight or branched alkyl substi- tuted o-B-unsaturated aldehydes can be used to provide, improve or modify savory, burnt, or meaty flavors (Pickenhagen and Velluz, 1982). Their application in the synthetic flavor should be investigated. A potato-/cabbage-like aroma has been observed in heated glucose- methionine mixtures (Arroyo and Lillard, 1970; Lindsay and Lau, 1972). The latter authors suggested that browning reaction produCts such as mercaptans and sulfides were probably responsible for the cabbage-like odor, while methional played a major role in imparting the boiled potato-like aroma. Therefore, methionine may be directly responsible for the ”Cooked Vegetables" aroma property associated with the synthetic flavor. The significance Of the volatile components in contributing to these aroma qualities will be discussed more fully in Chapter III. HVP, dry vegetables, and spices in the formulations of commercial beef flavors contributed directly to "Cooked Vegetables" and "Spicy/ Fragrant" aroma properties characterizing these samples. CONCLUSIONS The meaty aromas of the two synthetic meat flavor mixtures were not rated as being significantly different from that of the natural beef flavor, but all were rated significantly higher than those of the commercial beef flavor samples. Burnt and sulfurous, and cooked vegetables, garlic-like, and onion-like generally comprised the nonmeaty aroma qualities frequently associated with the synthetic meat flavors and commercial beef flavors, respectively. The natural beef flavor was described as being sweet, boiled meat, and brothy. Descriptive aroma evaluations further revealed that the synthetic meat flavor was characterized by having more "Toasted/Burnt" notes than the "ideal", natural and commercial meat/beef flavors, while the latter tended to have pronounced ”Spicy/Fragrant" and "Cooked Vegetables'I aroma characteristics. In comparison, the natural beef aroma was characterized as being more "Flat/Dull". 116 REFERENCES AOAC. 1975. "Official Methods of Analysis," 12th ed. Association of Official Analytical Chemists, Washington, DC. Arroyo, P.T. and Lillard, D.A. 1970. Identification of carbonyl and sulfur compounds from nonenzymatic browning reactions of glucose and sulfur-containing amino acids. J. Food Sci. 35:769. Batzer, O.F., Santoro, A.T., Tan, M.C., Landmann, W.A., and Schweigert, B.S. 1960. Precursors of beef flavor. J. Agric. Food Chem. 8: 498. Batzer, O.F.,Santoto, A.T., and Landmann, W.A. 1962. Identification of some flavor precursors., J. Agric. Food Chem. 10:94. Cochran, W.G. and Cox, G.M. (Ed.). 1957. "Experimental Designs." John Wiley and Sons, Inc., London. Duncan, 0.8. 1955. New multiple range and multiple F tests. Bio- metrics 11:1. Dunnett, C.W. 1964. New tables for multiple comparisons with a control. Biometrics 20:482. Gacula, M.C. and Singh, J. (Ed.). 1984. "Statistical Methods in Food and Consumer Research." Academic Press, New York. Galt, A.M. and MacLeod, G. 1983. The application of factor analysis to cooked beef aroma descriptors. J. Food Sci. 48:1354. Hsieh, Y.P.C., Pearson, A.M., and Magee, W.T. 1980a. Development of a synthetic meat flavor mixture by using surface response methodology. J. Food Sci. 45:1125. Gutcho, M.H. (Ed.). 1977. "Textured Protein Products." Noyes Data Corp., Park Ridge, NJ. Kuninaka, A. 1967. Flavor potentiators. In "Symp. Foods: The Chemistry and Physiology of Flavors," H.W. Schultz, E.A. Day, and L.M. Libbey (Eds.). AVI Publishing, Westport, CT. Lindsay, R.C. and Lao, V.K. 1972. Some reaction products from nonenzy- matic browning of glucose and methionine. J. Food Sci. 37:787. 117 118 MacLeod, G. and Coppock, B.M. 1978. Sensory properties of the aroma of beef cooked conventionally and by microwave radiation. J. Food Sci. 43:145. MacLeod, G. and Seyyedain-Ardebili, M. 1981. Natural and simulated meat flavors (with particular reference to beef). CRC Crit. Rev. Food Sci. Nutr. 14:309. Persson, T., von Sydow, E., and Akesson, C. 1973. Aroma of canned beef: Sensory properties. J. Food Sci. 38:386. Pickenhagen, W. and Velluz, A. 1982. a-B Unsaturated aldehydes and their use as aromatizing ingredients. Swiss Patent CH 632 650 A5. Schrodter, R. and Wolm, G. 1980. Studies on Optimal conditions for flavor formation in amino acid-glucose model systems. Nahrung 24: 175. Shahidi, F., Rubin, L.J., and D'Souza, L.A. 1986. Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation. CRC Crit. Rev. Food Sci. Nutr. 24:141. Weiner, C. 1972. Inorganic sulfide-carbohydrate reaction mixture. US Patent 3 645 754. Wasserman, A.E. and Gray, N. 1965. Meat flavor. I. Fractionation of water-soluble flavor precursors of beef. J. Food Sci. 30:801. Zaika, L.L., Wasserman, A.E., Monk, C.A., and Salay, J. 1968. Meat flavor. 2. Procedures for the separation of water-soluble beef aroma precursors. J. Food Sci. 33:53. CHAPTER II MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS. I. SENSORY EVALUATION ABSTRACT The investigation into the effects of pre-extrusion addition of meat flavor precursors on the sensory properties of a soy extrudate (15HH) revealed that there was a moderate, but significant improvement in "Meaty" flavor when compared to an unflavored extrudate (UFC). NO significant difference in meatiness was observed between 15HH and a commercial beef flavored extrudate (15H0). Neither the flavor precursor system nor the commercial beef flavor was entirely successful in masking the "Green" and "Beany" off-flavors of soy protein products. Except for saltiness where 15HO was rated significantly higher, no differences in "Roasted", "Sweet" or ”Bitter" notes were found among 15HH, 15HO, and UFC, nor when they were compared to a conceptualized "Ideal" meat flavored extrudate (IMF). All three extrudates were scored significantly lower in "Meaty" flavor but higher in ”Green" and "Beany" notes than ideally desirable. Subtle differences in moisture and fat contents, pH values, and browning indices 420nm were observed among 15HH, 15HO, and UFC. 119 INTRODUCTION Controlling off-flavor develOpment while successfully simulating desirable meat flavor in extruded soy protein products is a major factor preventing the more widespread use of extruded soy protein products as meat extenders or analogs (Gruelle, 1974; van den Ouweland and Schutte, 1978; Kinsella and Damodaran, 1980; Palkert, 1980; Kinsella, 1983; Kinsella et al., 1985). Flavor addition most commonly occurs after extrusion, either by hydrating the extrudate in a flavor medium followed by drying, or by spraying an oil and flavor mixture onto the dried extrudate (Blanchfield and Ovenden, 1974; Pagington, 1975; Williams et al., 1977; Kinsella et al., 1985). These methods, however, suffer from the disadvantage of involving an additional processing step. In addition, added flavors are not evenly distributed throughout the product (Fischetti, 1975), and can be lost during storage or through leaching while cooking in an aqueous medium (Blanchfield and Ovenden, 1974). Pre—extrusion addition or internal application of flavors to a soy mix is more practical, but extensive losses occur during processing due to steam volatilization of the flavor compounds at the exit port of the extruder and binding by proteins (Pagington, 1975; Williams et al., 1977; Palkert and Fagerson, 1980). The extent of loss varies with the compound (Palkert and Fagerson, 1980). Thus, flavor development from precursors during extrusion has been suggested as a solution by several 120 121 authors (Heath, 1972; Hashida, 1974; Coleman, 1975; Pagington, 1975). This latter technique has the unique potential of producing flavors characteristic of the degree of doneness of the meat to which the flavored TSP has been added (Heath, 1972). Several researchers have stated that the optimum conditions for the production of soy extrudate are often narrow (20-30 sec) (Williams et al., 1977), and may not correspond well to those for flavor develOpment (Blanchfield and Ovenden, 1974). Furthermore, undesirable flavors may develop during storage (Blanchfield and Ovenden, 1974; Heath, 1972). However, such information is frequently proprietary and unavailable to the general scientific community. To date, results of sensory or instrumental analyses of soy extrudate pre-extrusionally added with meat flavor precursors have not been published. With the more recent developments in meat flavor research as discussed in Chapter I, pre-extrusion addition of the meat flavor precursors developed by Hsieh et al. (1980) offered a challenging and viable alternative. This paper, therefore, constitutes the first of a three-part study on meat flavor development from added precursors during extrusion. The objective of this study was to examine the effects of pre- extrusion addition of meat flavor precursors on the sensory properties of a soy extrudate. These properties are discussed in relation to those of the extrudate pre-extrusionally flavored with a commercial beef flavor,zn1unflavored product, and a conceptualized "Ideal" meat flavored extrudate. A previous study (Chapter 1) formed the basis for the selection of the flavor systems examined. EXPERIMENTAL Material Defatted Soy Flour R Soyafluff 200W defatted soy flour (mesh size 100, protein dispersion index-moderate, 50-54% protein, 6-9% moisture, 1-1.5% fat, 36-28.5% carbohydrate, 5-7% ash; Central Soya Co., Fort Wayne, IN) was used in this study. Flavor Systems Meat flavor precursors (Hsieh et al., 1980) containing 17.1% reducing sugars, 16.0% amino acids, 2.7% nucleotide, 53.5% gelatin, and 10.7% salt was formulated in the laboratory. Commercial beef flavor (HO) containing beef extract, beef fat, natural flavoring, salt, sugar, caramel, disodium guanylate/inosinate, malto-dextrin, spice, and onion, was Obtained from a local supermarket. Detail descriptions of these flavor systems have been reported earlier (Chapter 1). Model System Study Thermal develOpment of meat aroma in a soy protein matrix on adding varying levels of the meat flavor precursor system was examined. Experimental results were used as a guide for establishing the level of addition of the precursor system in defatted soy flour for subsequent extrusion study. The results Of this part of the study, which were 122 123 preliminary in nature will not be discussed under "RESULTS AND DISCUSSION". Preparation Reaction mixtures for the model system study were prepared by careful delivery into 100 mL crimped-sealed serum-type reaction vial (Supelco Inc., Bellefonte, PA) with the components listed in Table 1 (in the order from left to right). Table 1. Chemical composition of model systems. Vial Water (9) Flavor Defatted soy Total no. precursors (g) flour (9) weight (g) 1 1.50 0.00 ( 5%)a 5.00 6.50 2 1.45 0.24 ( 5%) 4.81 6.50 3 1.40 0.46 (10%) 4.64 6.50 4 1 35 0.67 (15%) 4.48 6.50 5 1.30 0.87 (20%) 4.33 6.50 6 1 26 1.05 (25%) 4.19 6.50 aPercent weight, weight of defatted soy flour. Based on previous extrusion studies by Aguilera (1976), Maurice et al. (1976) and Palkert (1980), water was added at a level of 30% (wet basis) of the total weight of defatted soy flour. No correction was made for the presence of moisture (~6%) in the flour. Upon delivery of the flavor precursors, the mixture was sonicated (Ultrasonic Vibrator, Fisher Scientific Co., Fair Lawn, NJ) for 5 min to solubilize the chemical components. Due to the relatively small amount of water present, a considerable amount of the flavor precursors, particularly the gelatin, remained undissolved. Gradual addition of defatted soy flour was accomplished while stirring intermittently on a vortex stirrer 124 (Virtis 45 Homogenizer, The Virtis Co., Gardiner, NY). The reaction mixtures were conditioned overnight at 4°C. Subsequently, the serum reaction vials were heated individually in a glycol bath (Hi-TempTM Model 160, Fisher Scientific Co., Fair Lawn, NJ) at 220°C for 8 min. Duplicate sets of vials were prepared. After heating, the outsides of vials were washed with acetone and the vials stored at -20°C until ready for the ranking test. The crimp-sealed caps were replaced with MininertR valves (Supelco Inc., Bellefonte, PA) for ease of handling. The valves were set in a "closed" position at all times. RankingTest The test conditions, the six-member panel, and the general sample handling and coding procedures used in the model study and in subsequent evaluation of extrudates were described earlier (Chapter 1). Two sessions, a week apart, were conducted. During each session, the panelists were presented with six coded samples in a random order. Immediately before serving, the samples were heated on high for 20 sec in a Tappan microwave oven (Model 02216, Tappan Co., Manfield, OH). The panelists were requested to uncap, sniff, and rank the samples for meat aroma intensity (1-least intense to 6-most intense). Duplicate assessments by the six panelists were treated as representative of twelve panelists for the purpose of data analysis. The rank totals for the samples containing 0, 5, 10, 15, 20 and 25% of the flavor precursors were 22, 25, 31, 59, 56, and 59, respec- tively. Rank totals required for significance for 12 panelists and six treatments at the 5% level are <32 and >52 (Kramer, 1963). Therefore, 125 the flavor precursors were added at a level of 15% of the weight of the flour in the extrusion study. Similarly, the commercial beef flavor (HO) was added at a 15% level without further testing. Extrusion Study Preblending Flavor Systems with Defatted Soy Flour Because of the process design and the limited solubility of flavor precursors in water as mentioned earlier, the flavor systems were preblended with defatted soy flour before extrusion. Two flavored and one unflavored preblends of 8 kg each were formulated. The flavored preblends were prepared by initially mixing 1.2 kg of each of the flavor systems with 2 kg of the flour in a Hobart Mixer (Model K-200) set at speed one for 5 min. Thereafter, the remaining 4.8 kg of flour was added in three stages alternated with a 3-min mixing period. When the flour was completely added, mixing was continued for another 5 min to ensure uniform distribution of the flavor system in the soy matrix. An unflavored preblend was similarly prepared with 1.2 kg of defatted soy flour added in place of the flavor system. The preblends were prepared in the order of: unflavored, flavored with meat flavor precursors, followed by flavored with commercial beef flavor. All three preblends were placed in polyethylene bags and stored overnight at 4°C before being extruded. Extrusion Process The extrusion runs were carried out at the Gerber Products Company (Fremont, MI) with the assistance of their Food Product Development Team. The pilot plant extruder used was a Creusot-Loire twin screw 126 extruder (Model BC-45, Creusot-Loire, France) having the following specifications: barrel length 50 centimeter (cm), barrel diameter 5.5 cm, die diameter 0.4 cm, one zone electric heater, electrically heated die assembly, variable speed motor assembled drive unit capable of screw speeds from 110 to 150 revolutions per min. The screw profile was made up of 5 screw element sections as listed below from beginning to product discharge: Screw pitch (cm) Screw Element Length (cm) 5.0 20 .5 10 5 5 5 10 5 (cut flight element) 5 50' 3 2 1 1 The material to be extruded was fed into the extruder using a gravity feeder. Water for moistening the feed materials (the flavored and unflavored preblends) was fed through a line feeder to the mixing chamber of the mixing chamber of the extruder. Trial extrusion runs (feed moisture 22-28%, screw speed 110-150 rpm, barrel temperature 140-170°C) with the flavored and unflavored preblends revealed that the optimum condition for the production of extruded soy protein products did not coincide with the conditions necessary for optimum flavor development. The flavored preblends containing either the meat flavor precursors or the commercial beef flavor when extruded under the conditions used for the unflavored preblend produced an excessively burnt, charred and friable product. Rather than resorting to a compromise set of extrusion condition, the flavored and unflavored preblends were extruded using the following 127 set of conditions: Flavored Unflavored Feed moisture (%) (wet basis) 28 28 Screw speed (rpm) 130 150 Barrel temperature (°C) 155 160 The materials were extruded in the order described previously for the preblending of the flour flavor mixtures. The initial product (m2 kg) of each extrusion run was discarded with the remainder (m6 kg) being collected, and dried at 55°C for 10-15 min. The three extrudates prepared were: UFC - the unflavored product, and 15HH and 15HO - the products pre-extrusionally added with the precursor system and the commercial beef flavor, respectively. After drying, the extrudates were placed in polyethylene bags and stored at 4°C for subsequent testings. The elapsed time was approxi- mately three weeks. A representative 1.5 kg sample was randomly drawn from each extrudate. Subsequent test samples were obtained from the 1.5 kg sample. Chemical/Physical Analyses In preparation for the following analyses, 45 g Of each extrudate were finely ground in 15 9 portions (m1.5 min) using a Waring blender. The ground samples were used for moisture, fat,Ifii,and browning index determinations. Each test was carried out in triplicate. Moisture and fat determinations were carried out according to A.O.A.C. (1975) procedures, 24.003 and 24.005, respectively. The browning index was determined using a clear brown extract obtained by adding 20 mL of deionized water to a 5 9 sample in a test tube. The 128 content was stirred continuously for 1 min using a vortex stirrer and filtered through Whatman #2 filter paper followed by a membrane filter (0.45 uM MetricelR membrane filter) to remove any minute particles which may interfere with the absorbance reading. Absorbance of the extract was read at 420 nm using a SpectronicR 2000 (Bausch and Lomb, Rochester, NY). Browning index was expressed as absorbance 420 nm x 100. pH was determined using a standardized digital ionalyzer (Model 601A, Orion Research Inc., Cambridge, MA). Sensory Evaluation The three extrudates (UFC, 15HH, and 15HO) were profiled in terms of aroma ("Meaty", "Roasted”, "Green", and "Beany") and flavor-by-mouth ("Meaty", "Roasted", “Green", "Beany", "Sweet", "Salty", and "Bitter") on a 1 (none) to 10 (very pronounced) point intensity scale. The choice of the descriptors was limited to those which were reported to have significant influence on the sensory properties of soy extrudates intended for use as meat extenders or analogs (van den Ouweland and Schutte, 1978; Rackis, 1979; Palkert, 1980; Kinsella, 1983). For aroma evaluation, 10 g of each extrudate were hydrated with 20 mL of water for 10 min in a coded, covered plastic container. Subsequently, they were heated on high for 10 sec in the microwave oven and served immediately to the panelists. For evaluation of flavor-by-mouth, the extrudates were served as meat snacks without rehydration. A completely randomized block design was used in sample presenta- tion. Additionally, each panelist was requested to provide 5 sensory profile of a conceptualized "Ideal" meat flavored soy extrudate (IMF). 129 Water was provided for rinsing between samples to reduce carryover flavor. Statistical procedures and inferences as described in Chapter I were used for data analyses and interpretation. RESULTS AND DISCUSSION Chemical/Physical Analysis The chemical (% moisture and % fat) and physical (pH and browning index) data of the extrudates (UFC, 15HH, and 15HO) were statistically analyzed and compared (Table 2). Soy extrudate (15HH), flavored with meat flavor precursors was found to be significantly higher in browning index (81), and signifi- cantly lower in pH and moisture content as compared to 15HO or UFC at p<0.01. In contrast, pre-extrusion addition of the commercial beef flavor did not significantly (p<0.01) affect the moisture nor pH of the extrudate (15HO) as compared to the unflavored product (UFC). However, the fat content was found to be significantly (p<0.01) higher in 15HO than in either 15HH or UFC. The unflavored soy extrudate (UFC), on the other hand, was significantly (p<0.01) lower in fat content and browning index than the flavored extrudates. Browning Index (81) The Maillard reaction between amino acids and reducing sugars appeared to be chiefly responsible for the increased browning in 15HH (BI-142) as compared to 15HO (BI-108) and UFC (BI-73). Amino acids and reducing sugars were added initially at 2.4% and 2.7% (flour weight basis), respectively, in 15HH. Caramel, a commercial colorant for 130 131 Table 2. Comparisons of some chemical/physical data of an unflavored (UFC) and flavored (15HH and 15HO)a soy extrudates. Chemical/physical Soy extrudate Comparisonc prOperty . UFC 15HH 15HO Moisture (% 6.93 b 5.42 6.75 UFC 15HO > 15HH dry basis) 20.04 20.13 20.05 Fat (% dry basis) 0.42 0.46 0.54 15HO > 15HH > UFC 20.01 20.02 20.03 Browning index420nm 72.8 142.5 108.8 15HH > 15HO > UFC 23.0 26.4 25.3 pH 6.50 5.90 6.29 UFC 15HO > 15HH 20.13 20.15 20.10 a15HH and 15HO were prepared with the pre-extrusion addition of the meat flavor precursor system (Hsieh et al., 1980) and the commercial beef flavor (HO), respectively. See Experimental section C. bReported values were the means2standard deviations of triplicate analyses. CSamples were listed in decreasing order where underscored samples were not significantly (p<0.01) different as established using the Analysis of Variance and Duncan's Multiple Range Test. 132 textured soy protein products, was primarily responsible for the higher B1 in 15HO as compared to UFC. The colors of these products as observed visually were: UFC-yellow tan, 15HO-light brown, and 15HH-brown. LH Due to the short residence time (m9 sec) in the extruder, the residual unreacted amino acids were probably responsible for the lower pH value in 15HH (pH 5.9) as compared to 15HO (pH 6.3) and UFC (pH 6.5). The pH value of UFC was in close agreement with those reported for textured sunflower/soy flour (pH 6.5; Vasquez et al., 1979) and meat analogs (pH 6.5; Hegarty and Ahn, 1976). Moisture Shifting of the pH value to the isoelectric point (pH 4.5) of the soy protein as in the case of 15HH probably reduced the water binding capacity of the protein by affecting the magnitude of the net charge on the protein (Kuntz, 1971). This together with the length of drying (10-15 min at 55°C) which was not rigidly monitored, were the most probable factors contributing to the significantly lower moisture content in 15HH (5.4%) as compared to those of UFC (6.9%) and 15HO (6.8%). {at Beef fat, present in the commercial formulation of beef flavor (HO) was reflected in the higher fat content (0.54%) associated with the commercial beef flavored extrudate as compared to 15HH (0.46%) and UFC (0.42%). The difference in fat content among the latter two was 133 probably due to the presence of a higher amount of ether extractables (such as Maillard reaction products) other than fat in 15HH. The moisture and fat contents of UFC were within the maximum limits of reported values on textured soy flour, these being, 10% (max) for moisture and 1% (max) for fat (Company literature: Central Soya Co., Fort Wayne, IN). Sensory Evaluation Soy extrudates (15HH, 15HO, and UFC) and a conceptualized "Ideal" meat flavored extrudate (IMF) were evaluated for four aroma ("Meaty", "Roasted“, "Beany", and "Green") and seven flavor—by-mouth ("Meaty", ”Roasted", "Beany", "Green", "Sweet“, "Salty", and "Bitter") attributes on a 1 (none) to 10 (pronounced) point intensity scale. The sensory data were statistically analyzed and compared (Table 3). The aroma and flavor-by-mouth difference scores between (a) soy extrudate(s) and IMF, and (b) flavored extrudate(s) and unflavored extrudate are graphically presented in Figure 1A-D. ”Green'I and ”Beany" Pre-extrusion addition of either the meat flavor precursors or the commercial beef flavor was not entirely successful in masking the "Green" and "Beany" Off-flavor notes associated with soy protein products. The extrudates were all perceived as having a slight "Green” flavor with a moderately intense "Beany“ note. No significant (p<0.05) differences in the "Green" and "Beany" sensory scores were found among the soy extrudates. However, all three extrudates (15HH, 15HO, UFC) were scored significantly (p<0.05) higher in both of these attributes 134 Table 3. Comparisons of the sensory intensity scores of an "Ideal” meat flavored (IMF), an unflavored (UFC), and flavored (15HH and 15H0)a soy extrudates. Unflavored and flavored soy extrudate Sensory property IMF UFC 15HH 15HO Comparisonc AROMA d Meaty 8.0 b 2.0 * 3.3 * 3.3 * 15HH 15HO > UFC 20.9 21.1 21.4 21.5 Roasted 6.2 6.7 5.2 4.3 UFC 15HH 15H0d 21.8 21.8 21.8 21.5 Green 1.0 3.0 3.0 3.5 15HO 15HH UFCd 20.0 22.8** 21.7** 21.4** Beany 1.7 6.0 5.2 4.5 UFC 15HH 15H0d 20.8 21.9** 21.9** 21.6** FLAVOR-BY-MOUTH Meaty 8.2 1.5 3.2 3.7 15HO 15HH > UFCe 20.8 20.6* 21.0 21.4* Roasted 6.3 5.0 4.7 4.3 UFC 15HH 15HOd 20.6 21.9 21.6 21.5 Green 1.2 3.3 3.3 4.0 15HO UFC 15HHe 20.4 21.6** 21.8** 21.1** Beany 2.0 5.3 5.2 5.3 UFC 15HO 15HHe 21.1 21.9** 21.8** 21.9** Sweet 2.8 1.3 2.3 2.5 15HO 15HH UFCd 21.7 20.5 21.2 21.4 Salty 4.8 1.8 2.5 6.7 15HO > 15HH UFCe 21.6 21.2* +1.1* 21.5** Bitter 1.3 2.8 2.7 1.5 UFC 15HH 15HOd 20.5 21.0 21.5 20.6 a15HH and 15HO were prepared with the pre-extrusion addition of the meat flavor precursor system (Hsieh et al., 1980) and the commercial beef flavor (HO), respectively. Sensory intensity scores were rated on a 1 (none) to 10 (very pronounced) point intensity scale. See Experimental section C. means2standard deviations of a 6-member panel. Values reported were the 135 Table 3 (cont'd.) CSamples were listed in decreasing order of intensity where underscored samples were not significantly different at dp. >33. 2:22.: mac; .9: 93:39.23 . .33 .o I - - - I I See; 33.: Gee: .893 0. >253 052280 moo; .293qu 9323323 . c3333.. 932323 .u . . . 1 gen; 3038a 03!. no.3 I :6 I 3:: I 5:0 I 5:: I .25 12073.32... 2:225. moo; 33 9325223 . .23 .1 ~\ \ . x. . , 5.8 ~\\\\\~.> \\,\\ \\\\ \\‘ WW7 ~r—e’WJ 4 i \\\ \\,‘>\.“‘.‘\"\ FIever-by-meuih Olliereoce Score to»; 308.2. Pee: 03.: nice. 0. $2073.33... 0522.3 moo; .2233: mused-.23 c3333.. 9:22.23 Fievor-by-meuih Oliierence Score gee; menu-ed 032. 0:3 920.. I So I 5:: H 3:0 I 3:: I 5:0 (5) -mouth difference scores between soy extrudate(s) and IMF (A and B), and flavored extrudate and unflavored extrudate (C and D). Aroma and flavor-by Figure 1. 137 when compared to the conceptualized "Ideal" model (IMF). A slightly higher tolerance for the "Beany" rather than the "Green" off-flavor was found among the panelists. This was being reflected in the higher intensity scores for the "Beany" attribute in IMF. As reported by Rackis et al. (1979), n-hexanal, cis-3-hexenal, and ethyl vinyl ketone are the major contributors to the "Green/Grassy" off-flavor notes in soy protein products, whereas n-pentylfuran and cis- or trans-Z-(l-pentenyl)furan are primarily responsible for the "Beany" note. In addition, the "Green" and "Beany" off-flavors may be accentuated by the presences of C5-C7 alcohols (Rackis et al., 1979). The flavor threshold values in oil are in the range of 0.11-0.35 ppm (Grosch and Laskawy, 1975; Chang et al., 1966) and 2-10 ppm (Chang et al., 1966; Arai et al., 1970; Ho et al., 1978) for the compounds responsible for the "Green/Grassy" and "Beany" off-flavors, respectively. "Meaty" and "Roasted" The soy extrudate, 15HH prepared with the pre-extrusion addition of the flavor precursors, was scored significantly (p<0.05) higher in meatiness than the unflavored extrudate (UFC). However, no significant (p<0.05) difference in meatiness was found between 15HH and 15HO. The flavored soy extrudates (15HH and 15H0) were described as having a slight "Meaty" flavor. The short residence time (m9 sec) in the extruder may have prevented the "Meaty" flavor from being fully developed in 15HH. All three extrudates were scored significantly (p<0.05) lower in "Meaty" flavor than ideally desirable. In comparing the "Roasted" aroma and flavor-by-mouth intensity scores of the three extrudates (15HH, 15HO, and UFC), generally higher 138 intensity scores were obtained for the aroma than for the flavor-by- mouth evaluation. This may imply that the roasted quality of the extrudates was more of a aromatic property rather than a taste property. Similar observations were made by Palkert (1980) who reported that "Beany", "Cereal", "Roasted" were the important aroma notes in textured soy protein product, whereas "Cereal", "Beany", and "Sweet" were the prominent flavor notes. Nevertheless, in terms of the "Roasted" property, no significant difference (p<0.05) was found among the three extrudates and they were not significantly different from the "Ideal" model at p<0.05. The contribution of volatile Maillard reaction products to the "Meaty" and "Roasted" flavor notes of the extrudates will be discussed in Chapter III. The sensory properties of the volatile Maillard reaction products have been reviewed by Vernin (1982) and Fors (1983). Wilson (1975) reported that carbonyl compounds (such as sugars, sugar phosphates, and Strecker aldehydes) are responsible for supplying a roasted, burnt note in synthetic meat flavors. Some thiol-substituted furan and thiophene derivatives were reported to provide a "Meaty" note (Gruelle, 1974; van den Ouweland and Peer, 1975). j§weetflj "SaltyP, and "Bitter" 0n evaluating the three basic tastes, no (p<0.05) significant difference was found among the three extrudates (UFC, 15HH, 15H0) nor when they were compared with the "Ideal" extrudate (IMF) for the "Sweet" and "Bitter" notes. In general, the flavored extrudates had more pronounced "Sweet" notes than the unflavored product (UFC). Bitterness 139 was more perceptible in 15HH and UFC than in 15HO. The commercial beef flavored soy extrudate (15H0). however, was found to be significantly (p<0.01) higher in saltiness than either 15HH or UFC. The soy extrudate, 15HO, was also rated significantly (p<0.01) higher in saltiness than the "Ideal" extrudate (IMF), whereas 15HH and UFC were rated significantly (p<0.05) lower. Rakosky (1974) reported that salt has a masking effect on the off-flavors of soy protein products. This effect was observed in 15H0. Sessa et al. (1976, 1977) concluded that oxidation products of phosphatidylcholines are largely responsible for the inherent bitter taste of soy protein products (Rackis, 1979). Phenolic acids (Arai et al., 1966), ethyl-a-D-galactopyranoside and L-tryptophan (Honig et al., 1971), and daidzein, glycetein 7-d-O-glucoside, and genestein (Huang et al., 1981) may also contribute to or accentuate the bitter taste. The differences in the intensity scores for the "Sweet" and "Salty" notes were directly attributed to the compositional differences of the starting materials. 15HH was formulated with ~2.7% of reducing sugars and ~1.6% of salt. 15HO, on the other hand, was formulated with m2.0% of sugar and m3.0% of salt. Using Stevens' Law, the desired level of salt addition was estimated to be m2.3%. The percentages were expressed as weight/weight of soy flour. GENERAL COMMENTS In retrospect, the meat flavor precursors added at a level of 15% to the defatted soy flour as pre-determined using a heated model system, may be an overestimation. More discriminatory testings should be carried out to monitor meat flavor development under varying combina- tions of precursors formulations and extrusion conditions. Surface response methodology may prove to be an invaluable tool (Box and Wilson, 1951). Pre-extrusion addition of Maillard reaction intermediates derived from the meat flavor precursors may offer a solution to the short residence time encountered in the extruder for flavor development. In general, both the flavored extrudates (15HH and 15H0) were perceived as having a slight "Meaty" flavor which was found lacking in the unflavored extrudate (UFC). All three extrudates (UFC, 15HH, and 15H0) were rated as having a moderately intense "Roasted" and "Beany", and a slight "Green" flavor. Bitterness was not a problem associated with these extrudates. The "Salty" note was moderately intense in 15HO but was not noticeable in 15HH and UFC. In comparison, the "Ideal" meat flavored soy extrudate (IMF) was characterized as having a pronounced ”Meaty", moderately intense "Roasted", a slight to moderate "Salty", and an imperceptible "Green", "Beany" and "Bitter" flavor. In view of the above findings, pre-extrusion addition of the precursor system was moderately successful in imparting a "Meaty" 140 141 flavor to the soy extrudate under the extrusion condition employed. These data indicate that the pre-extrusion addition of meat flavor precursors to extruded soy protein products is a technically viable concept that could be utilized to produce meat-like flavors in soy protein products but probably will require carefully-balanced formula- tions and extrusion conditions. REFERENCES AOAC. 1975. "Official Methods of Analysis," 12th ed. Association of Official Analytical Chemists, Washington, DC. Aguilera, J.M. 1976. Texturization of foods: Raw materials, processes and products. Ph.D. Dissertation, Cornell University, Ithaca, NY. Arai, S., Noguchi, M., Kaji, M., Kato, H., and Fujimaki, M. 1970. n-Hexanal and some volatile alcohols, their distribution in raw soybean tissues and formation in crude soybean concentrate by lipoxygenase. Agric. Biol. Chem. 32:1420. Blanchfield, J.R. and Ovenden, C. 1974. Problems of flavoring extruded snack foods. Food Manufacture 49(1):27. Box, G.E.P. and Wilson, K.B. 1951. On the experimental attainment of optimum conditions. J. Roy. Stat. Soc. 313:1. Chang, S.S., Smouse, T.H., Krishnamurthy, B.D., Mookherjee, B.D. and Reddy, B.R. 1966. Isolation and identification of 2-pentylfuran as contributing to the reversion flavor of soybean oil. Chem. and Ind. (London) p. 1926. Coleman, R.J. 1975. Vegetable protein-A delayed birth? J. Am. Oil Chem. Soc 52:238A. Fischetti, F. 1975. Flavoring textured soy proteins. Food Prod. Dev. 9 6):64. Fors, S. 1983. Sensory properties of volatile Maillard reaction products and related compounds. In "Maillard Reaction in Foods and Nutrition," G.R. Waller and M.S. Feather (Ed.), p. 185. ACS Symp. Series No. 215:287. Americal Chemical Society, Washington, DC. Grosch, W. and Laskawy, G. 1975. Differences in the amount and range of volatile carbonyl compounds formed by lipoxygenase isoenzyme from soybeans. J. Agric. Food Chem. 23:791. Greuelle, E.H. 1975. Some aspects of research in the applications of soy proteins in foods. J. Am. Oil Chem. Soc. 51:98A. Hashida, W. 1974. Flavor potentiation in meat analogs. Food Trade Rev. 44(1):21. 142 143 Heath, H.B. 1972. Flavors in novel foods. Food Manufacture 47(1): 21. Hegarty, P.V.J. and Ahn, P.C. 1976. Nutritional comparisons between a soy-based meat analog and ground beef in the unheated and heated states. J. Food Sci. 41:1133. Ho, C.-T., Smagula, M., and Chang, S.S. 1978. The synthesis of 2-(1-phenyl)furan and its relationship to the reversion flavor of soybean oil. J. Am. Oil Chem. Soc. 55:233. Honig, O.H., Rackis, J.J., and Sessa, D.J. 1971. Isolation of ethyl 2-d-galactopyranoside and pinitol from hexane-ethanol extracted soybean flakes. J. Agric. Food Chem. 19:543. Hsieh, Y.P.C., Pearson, A.M., and Magee, W.T. 1980. DevelOpment of synthetic meat flavor mixture by using surface response methodology. J. Food Sci. 45:1125. Huang, A.-S., Hsieh, 0.A.-L., and Chang, S.S. 1981. Characterization of the nonvolatile minor constituents responsible for the objection- able taste of defatted soybean flour. J. Food Sci. 47:19. Kinsella, J.E. 1983. Protein texturization, fabrication and flavoring. CRC Handbook of Nutritional Supplements 1:35. Kinsella, J.E. and Damodaran, S. 1980. Flavor problem in soy proteins: Origin, nature, control and binding phenomena. In "Analysis and Control of Less Desirable Flavors in Foods," G. Charalambous, (Ed.), p. 95. Academic Press, New York. Kinsella, J.E., Damodaran, 5., and German, B. 1985. Physicochemical and functional properties of oilseed proteins. In "New Protein Foods, Vol. 5," A.M. Altschul, H.L. Wilcke, (Eds.), p. 107. Academic Press, New York. Kramer, K.H. 1963. Tables for constructing confidence limits for the multiple correlation coefficient. J. Am. Stat. Assoc. 8:1082. Kuntz, 1.0. 1971. Hydration of macromolecules III. Hydration of polypeptides. J. Am. Chem. Soc. 93:2514. Maurice, T., Burgess, L.D. and Stanley, D.N. 1976. Texture evaluation of extruded products. Can. Inst. Food Sci. Technol. J. 9:173. Palkert, P.E. 1980. The determination of flavor retention and native volatiles in pre-extrusion flavored textured soy protein. Ph.D. Dissertation, University of Massachusetts, Amherst, MA. Palkert, P.E. and Fagerson, 1.5. 1980. Determination of flavor retention in pre-extrusion flavored textured soy protein. J. Food Sci. 45:526. 144 Pagington, J.S. 1975. Flavoring and production of extruded soy protein. Inter. Flavors and Food Add. 6:278. Rackis, J.S., Sessa, D.J., and Honig, D.H. 1979. Flavor problems of vegetable food proteins. J. Am. Oil Chem. Soc. 56:262. Rakosky, J. 1974. Soy grits, flour, concentrates, and isolates in meat products. J. Am. Oil Chem. Soc. 51:123A. Schutte, L. and van den Ouweland, G.A.M. 1979. Flavor problems in the application of soy protein materials. J. Am. Oil Chem. Soc. 56:289. Sessa, D.J., Gardner, H.W., Kleiman, R., and Weisleder, D. 1977. Oxygenated fatty acid constituents of soybean phosphatidylcholines. Lipids 12:613. Sessa, D.J., Warner, K., and Rackis, J.J. 1976. Oxidized phospho- tidylcholines from defatted soybean flakes taste bitter. J. Agric. Food Chem. 24:16. van den Ouweland, G.A.M. and Schutte, L. 1978. Flavor problems in the application of soy protein materials as meat substitutes. In "Flavors of Foods and Beverages, Chemistry and Technology," G. Charalambous and G.E. Inglett (Eds.), p. 34. Academic Press, New York. Vasquez, M., Sanchez, F., Hiche, E., and Yanez, E. 1979. Sensory evaluation of textured sunflower/soy protein. J. Food Sci. 44:1717. Vernin, G. (Ed.) 1982. "The chemistry of heterocyclic flavoring and aroma compounds." Ellis Horwood Ltd., Chichester, UK. Williams, M.A., Horn, R.E., and Rugala, R.P. 1977. Extrusion. Part 1. Food Eng. 46(9):99. Wilson, R.A. 1975. A review of thermally produced imitation meat flavors. J. Agric. Food Chem. 23:1032. CHAPTER III MEAT FLAVOR GENERATION IN EXTRUDED SOY PROTEIN PRODUCTS. II. CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRIC ANALYSIS OF VOLATILE COMPONENTS ABSTRACT The formation of desirable volatile components as influenced by the pre-extrusion addition of meat flavor precursors in a soy extrudate (15HH) was investigated. Volatile identification by gas chromatography- mass spectrometry and computerized spectra matching of catalogued flavor compounds revealed the formation of substantially higher levels of 2- and 3-methylbutanal, 2-pentanone, and dimethyltrisulfide and of 27 new components including pyrazines, thiols, furans and furanones in 15HH as compared to an unflavored soy extrudate (UFC). Only four volatile components were found to be common to both 15HH and the synthetic meat flavor (HH), a thermally generated flavor mixture from the precursors used in 15HH. The volatile isolates of 15HH consisted mainly of aldehydes (30.7%), ketones (20.8%), thiols (15.8%) and pyrazines (7.2%). UFC consisted predominantly of pyrazines (16%), while 15HH was composed of aldehydes (21.8%), alcohols (12.9%), and acids (9.8%). A total of 59, 55, and 29 volatile components were identified in 15HH, UFC, and HH, respectively. Twenty-four of the unflavored soy volatiles were identified for the first time in textured soy proteins. The relative 145 146 significance of the identified components to the aroma qualities of 15HH, UFC, and HH are discussed along with their probable precursors. INTRODUCTION Approximately 750 compounds have been identified in the volatile fractions extracted from cooked beef (MacLeod and Seyyedain-Ardibili, 1981; Shahidi et al., 1986; MacLeod and Ames, 1986, 1987; Vercellotti et al., 1987; St. Angelo et al., 1987). Although their relative significance is unclear, oxygen-, nitrogen-, and/or sulfur-containing compounds, mostly cyclic Maillard reaction products, have been repeatedly suggested as being the principal contributor to meat flavor. In contrast, the flavor volatiles of soy protein products (SPPs) have not been investigated as extensively. Thus far, some 250 compounds have been identified in the volatile fractions of SPPs. Numerous researchers have examined the flavor volatiles of raw soybean (Arai et al., 1966b; Arai et al., 1967; Badenhop and Wilkens, 1969; Mattick and Hand, 1969; Honig and Rackis, 1975), soybean milk (Wilkens and Lin, 1970a), soy flour (Fujimaki et al., 1965; Arai et al., 1966a; Sessa et al., 1969; Hsieh et al., 1981), and soy protein concentrate (Arai et al., 1970). However, there have been only a few studies directed toward the identification of the flavor volatiles of heated SPPs. These studies have been limited to deep-fat fried soybeans (Wilkens and Lin, 1970), roasted soybeans (Miyrata et al., 1977; Kato et al., 1981), and heated soybeans (190°C/20 min) (Rosario et al., 1984). There has been only one report pertaining to 147 148 the flavor analysis of textured soy protein (Palkert, 1980). Qvist and von Sydow (1974) in their analysis of the volatile components of unconventional proteins, offered the only comparison of flavor volatiles of heated soy protein isolate and heated beef. Reportedly, the concentrations of C4-C6 aldehydes and 2-methylpropanal were much higher in heated soy isolate. Furans were more frequently detected and at higher concentrations in the heated soy product. On the other hand, sulfides (hydrogen-, dimethyl-, and ethylene-), and thiols (methane- and ethane-) were present in larger concentrations in heated beef, while methyldisulfide and thiophene were present in higher concentrations in the heated soy isolate. In general, the concentrations of almost all volatiles (except alcohols) increased on heating, indepen- dent of protein source. The primary objective of this study was to investigate the formation of desirable volatile components as influenced by the pre-extrusion addition of flavor precursors in a soy extrudate (15HH). The specific objectives were (a) to provide some chemical information on the native volatiles of an unflavored soy extrudate (UFC) and the synthetic meat flavor (HH), a thermally generated flavor mixture from the precursors used in 15HH, and (b) to discuss the relative significance of the identified volatiles to the aroma qualities of 15HH, 15HO, and HH. The preparations and sensory properties of the soy extrudates (Chapter II) and the synthetic meat flavor (HH) have been reported earlier. EXPERIMENTAL Sample Sources and Descriptions The formulations, extrusion conditions, and sensory properties of the flavored (15HH) and unflavored (UFC) soy extrudates have been described in Chapter II. The flavored soy extrudate (15HH) was formulated with the meat flavor precursor system previously described by Hsieh et al. (1980a) after adding it to the defatted soy flour at a level of 15% (w/w). The synthetic meat flavor (HH), an autoclaved mixture of the precursor system (Hsieh et al., 1980a) consisting of amino acids, reducing sugars, 5'-nucleotide, and glycoprotein, has been described and sensorially evaluated in Chapter I. Isolation and Concentration of Volatile Components Volatile Isolates of Soy Extrudates (HH and UFC) The soy extrudates to be analyzed were ground in 50 9 portions for 5 sec in a Waring blender with a rheostat setting at 45. A 150 g aliquot each of the ground samples were mixed with 1.5 L of deionized water in a 2.5 L round bottom flask. Antifoam A concentrate (0.30 9) (Sigma Chemical Co., St. Louis, MO) was added to prevent foaming. The R soy extrudates were extracted with 30 mL of Nanograde diethyl ether (Mallinkrodt, Inc., Paris, KY) for 4 hr in a modified Likens and 149 150 Nickerson (1964) apparatus (Kontes Glass, Vineland, NJ) as described by MacLeod and Cave (1975). The ether extract was dried over anhydrous sodium sulfate and concentrated to 0.2 mL in a stream of nitrogen at a flow rate of 60 mL/min. Volatile Isolate of Synthetic Meat Flavor (HH) A 25 mL aliquot of the autoclaved mixture was diluted with an equal volume of deionized water. The water components were extracted in diether ethyl and concentrated as described above. The use of an antifoaming agent was not necessary in this instance. Blank Volatile Isolates Two blank volatile isolates each for the soy extrudates (15HH and UFC) and the synthetic meat flavor (HH) were obtained using deionized water in place of the samples during solvent extraction. Capillary Gas Chromatography-Mass Spectrometry (GC-MS) Volatile components were separated and identified using a Finnigan 4021 GC-MS system. A high performance 50 m x 0.32 mm i.d. fused silica OV—101 (0.52 um film thickness) capillary column was used for separation. The column temperature was held at 40°C for 1 min, and then increased by SOC/min to a holding temperature of 2100C for 6.4 min. Helium was used as the carrier gas with a head pressure of 0.8 kgf/cmz. The injection temperature was 250°C and a 3 uL aliquot of each of the isolates was injected using a split ratio of 30:1. The mass spectrometer was operated under the E1 mode using the following conditions: ionization voltage, 73.3 eV; electronic multiplier 151 voltage, 1432 V; source and line temperature, 250°C; scanning range, 34-400 mass units, at 0.9 sec/cycle (repetitive throughout run). The identification of the volatile components was based on computer matching (>80%) of full or partial mass spectra of compounds catalogued in a specialized user's flavor library using the library program of the INCOS data system. Identifications were also made or confirmed by comparing experimental mass spectra with those of authentic compounds (see Appendix A) or published spectra (Stenhagen et al., 1974; Jennings and Shibamoto, 1980; Vernin, 1982). Mass spectral identifications were considered tentative when they were based solely on computer matching (70-75%) of catalogued compounds. Kovats retention indices (Jennings and Shibamoto, 1980) of many volatile components on OV-101 were included. The ion counts of identified volatile components were expressed as percentage of the total ion counts or relative percent abundance (RPA). The contributions of solvent and contaminant ions were not included in the total ion counts. RESULTS AND DISCUSSION The volatile components identified by capillary GC-MS are listed in Table 1. Kovats retention indices (Jennings and Shibamoto, 1980) of some of these components on OV-101 are included in the table, and they confirmed the general elution order. To assist in the following discussion, published information on the odor descriptions characteri- zing some of these compounds and/or their occurrences in beef/soy products are provided. The blank isolates showed that silicon- containing compounds, such as octamethylcyclotetrasiloxane, 2-(tri- methylsilyl)benzoic acid, and other trimethylsilyl derivatives, were contaminant compounds. Their origins, e.g. heated glass, silylating agent, septum or column bleed, have been discussed previously (Jeonetal et al., 1976; Galt and MacLeod, 1984; Jeonetal et al., 1976). In the soy extrudate extracts, the antifoaming agent was the major source for these silicon derivatives (Jeonetal et al., 1976; Palkert, 1980). Reconstructed ion chromatograms displaying the elution patterns of the volatile components are presented in Figure 1a-c. Table 2 is a summarized comparison of the results extracted from Table 1. The number of unidentified compounds (and their relative percent abundances) associated with the samples were as follows: 13 (3.1%) for the flavored soy extrudate (15HH), 26 (53.8%) for the unflavored soy extrudate (UFC), and 18 (39.7%) for the synthetic meat 152 153 «m .mm.~m.m~ Ammvem.o A©w~v_o=axaz-m mm .Nm.Hm ANHV .om.o~.m~ HH.oH ucmcwmwu Aomvofl.m Aemvmu.o Ammmv_o=axaz-H m mm megmzum .fim.©m.mu HH.oH .xmmacu Ammvmfl.o NAmN©v_o-N-=mb=aa-e mm.¢m .Hm.om mH .mm.m~.m~ .NH.HH.oH AGH Hm.o Ammvefl.o Aom~v_ocau=aa-fi HH.oH Awm m¢.o ”_o_ua:ap=m-m.~ 2N.cm.m~ HH.oH ANHVNH.O ANHVQN.¢ NUAHNGV -ngpae-m._o=au=m-m mm .mm.om.mm HH.oH Aomvm~.o -Pscyas-m .Focauam-~ -Axxocum Ammvmo.o -_»;uae-fiv-fi ._o=aaoca-~ Aofivmm.o ”-2xozam-~ ._o=aaoca-H Aomvmfi.o u-opamucae-~ ._o=o;pm Amfivxo.o -sxoaoca-~ ._o=a;um msozous< Amqvqm.o N-,»;ume-¢.c_ua awoempcaa-m Afimvom.fi Wampum _s;um .cwua u_EanLau Amvxo.o ~u_ua ucowuacaaoca mm .om.mN.NN HH.oH UANV3©©.H UAHHVnHm.o aAmvnHm.H uwum avuaa< mmMFWM\maHu< xom ymmm Aumzv mflmucmcwwmmv wumuacpxm szmAV Azzv mum_w_ucmu_ mcowaawcommc xom manuscpxm co>mP$ Home pcmcoaeou >Fm:o_>wca couo cmco>m—w:: zom vmco>m_u ovumgucxm w__pmpo> .mumvzcwxm xom umco>mpmcz can .AIImHV mumuzcuxm xom cmco>mFm .Azzv Lo>m_w acme u_um;uczm cw umwmvucmu_ mucmcoasoo mpwum~o> .H «Peak 154 mm .vm.mm .mm.Hm .om.om .mm.¢~.- mm .vm.~m.mm mm.~m mm.Hm mm afiv apxuwm .ucmmcsq .cmmgw may ucmmmmp :3 MH .u_u=ac .N~.HH.OH meocum ma AHV :mwcm .NH.HH.O~ .ucgzm m~.HH.oH H~.oH Amv Agmpmm .u=m>_om paupsmgu Afiv spxacm .cmmcm .uccam Amv msocawpzm .xpaaz Aev umpmmoc HH.oH .“cgsm Amv 6:22: m.uou AHV s_xuwm mH.HH.oH .ucczm Amavmm.o onmm.o Amvfim.o Amvmm.o AHNVON.H Aemvom.c AHVMN.HN Ammvom.o Amfivuo.o Amvfio.¢fi Amvmm.¢H Afifivmo.u Ammvmm.o Aom~vpacmxaz N-,»;ume_u -¢.N .pocmucma Pocmucma "-Ao_;u -pxzumev-m ._m:maoca upxzumum .pmcoazm -pxgums-m .pmcmusm -ngbas-m .Pmcaazm muo>xmou< ~_o-m-cxxaz-fi _ocmxmz-m A.u.»=ouv H apnmc 155 mH .NH.~H.OH HH.oH mm HH.o~ AHV 6_..aume .amwzm ANH .mv acospm .xuuaz Amv ecospa mm .ummzm .Nm.Hm.mN .mcocum . Aev mm Hm mH axw_-c=oe_a .om.mN.HN .Nfi.~a.ofi .ommzm ANH.mw xmmmc .cwmco AomVNN.H Aomvmm.o Ammvko.fi Aomvmm.o Ammvofi.o Amvkm.o Anmvoo.o Amvflm.o AOHVNN.O Mm“ mo.o mm 50.0 Ammvcfi.o H-,»;pme_u-¢.m .mcopaa: "-_»;uaewcu -m.¢.e .mcmxm:-~ "-pxgume -mcumu-m.m.~.m .mcmxm: u-_xcume_u-m.m .mcmxm: H-chumewcnv.m .mcmxm: "Aooovmcmxm: H-szums -mcump-¢.m.~.m .mcmucma ”-ngame-m .mcmpcma "-xxoaocm-~ .mcmusm uxxogum-~ .mcmuzm -ngumE-~-»xosuws-H .mcwuam -zxoguw-~ .mcmaocm ”-ngme-N-Xxo;qu-N .mcmaoca -xxogum_e-fi.~ .mcaguw mzommz mcxzmupmNcmm ”Pocmxm:-m A.u.u=oav H a_aah 156 em.mm.mm mm.mm.m~ mm NH.~H.oH NH.HH.oH mH .m~.-.ofi ma .NH.HH.o~ mfi .NH.HH.oH m“ .NH.HH.O~ mH .NH.HH.oH AHV cameo .uccsm Amv xumms .xyxuwm .ummzm .xgmuaam Aqv xcabuam Amv Acmumm .ucmmmm_a:= Amy 286623 .xcmn mcwsoumn .sc.=.. mcogum Amy mummz AmHVmH.o Ammvmm.o Aflmvfim.o Amevmfi.o Afivmo.o Aemvmm.H Ammvmfi.o Amqvmfl.o Ammvom.o Aevfim.om Aafiva.o Ammve~.o Ammvmo.o Afivo~.c Ammvmo.H Ammvmo.o ANV~M.N onflq.o Amquo.o hmuovmcocmucmaum Ammov->xocv>;-m .mcocmuzmlm N-,»;paswu-m.m -xxocuxzue .mcocmgzmum mmZOme upxcume .m:m~cmm mcmNcmm ”mauve“ -muamcopuxu-m.m.~ ”-quuo .mcmxmzopuzu u-_>xmn .mcmxm;o_uxu H-Apxucmapxgume -evum .mcmxmsopuxu H-,»;Bae-m .mcmucmqopuxu ”Aoofifivaeaamuca ”-_»;pas_cu -m.o.¢.a=a=oz-~ Aoomvmcabuo ”-_»;3as_u-o.~ .acmaam: A.u.g=oav 3 mpgap 157 mm.~m.mm Hm mm mm.¢m.mm .Hm.om.mm mm .¢m.mm.mm .om.mm.mm Hm mm .Hm.om.HN Hm NH.HH.oH H~.oH NH “H.o~ NH.H~.OH N~.HH.OH NH NH.~H.o~ NH.-.OH Amy xcmmm HmH aEaH .xcmnnzc .m:_H: AHV Hmmzm .Hcmmcza .cmmcu Hmw ;m_:mmc -xcmmn .axHH -mu_coowH ANHV Hmsmgmu HHV soocgmze .cmmcw HHH HHHaHm .Hcmmcaa .zmmcw HNHH Pmsmcou HHHgmHHm Hmqum.o Hmvoo.o HmHHHm.H Ammvom.~ HmHHNN.o HmHHHN.o HmmHHN.o HNNHem.o HHHmm.H Acevum.o Hovao.o HmHVHN.o HeHHmm.o HmmmH-HHH=aa-N .cacsu HumoH-HH;HaeHe-m.N .cacsu H-ngumsum .wcmpoxowaum.H -HHEHaEHu-m.N .acacon Hmcmcwxo muHHUHUOHHHH: quzHxo mcocmucmao_uxu mcowumcmuuo-m.m HmmmvacocaHuo-N HmNHuzzH acoHaH ngHmz a Ammmvmcocqumz-m mcocmxmzum Amuxvmcocmxmz-~ upxgumsuw .mcocmucmm-m H.G.Hcouv H aHaaH 158 AmHV :mmcm .HHHuHm .umwzm HmHH mHHH mH nus: 3ch .NH.HH.oH .HcamcHMHw< Hemvmo.o H-szHaE-N .acHuHcHa e HumHaHHuH kummoc .ucmmmmFQ .LaHHHm .Aumumcu mH -cmucouv .NH.HH.oH aHH> HoHHmo.o ”acHuHcHa Hemvo¢.o -oceHgHu-m.e .aHoNauHEH-zH muHHHHUOmHHH: quzH .xcwuusn HH.oH .Hccsm Hmquo.c HmNoHH-HH;Ha .aHao.=H-N mH ANHV :mmcm H-szume .NH.HH.oH .Hasmcau HmNHmH.o -N-ocuH;Hu .acocacsa-H:NHm H-»xocux; Homvmo.o -m-occH;Hu .mcoeacsu-HzmvN HHHHGN.O -Hnga-m .aco=a23H-H:mHN mH Hmv uHucac wm.mm.mm .NH.HH.oH .HHHa. .MHWO HNNHoN.N HHmvH©.o HHmka.H HmHmHHacsccsu-N m m_xu:mxm:o; .ucmcmmcm mm NH.HH.oH .HacoHa HwHHmo.o HNQHV-HHQQLQ-=-N .cacsa HH.oH HemHmH.o HGHHHo.o "-Ho_;Ha=a;HaEH-N .cacsu H.u.H=OUH H aHnaH 159 mm.mm.om ¢m.~m .mm.mm.mm em .mm.~m .mm.~m.mm em .mm.~m .m~.H~.oN em.mm .mH.NN.oN AmHv mmHT—ou .HHHacc NH.HH.oH .xquHm Hmv mHHH upcw>pom .mazc vmummoz HmHH Hmsogmu .amozm HH.: mH umummoc .NH.HH.oH .xuuaz va xcmumm .u:m>—om .cmpuzn panama Ach cwmcm .pmmocnxumwe .xumaz Amy azucmm .umummom HeH mHHH HH.oH -oumuoa Hey HHHzc .umumoom Hev mxHH NH.HH.oH -oumuom mH .NH.HH.oH mH.NH Homvmm.o HHmHHN.H HHmHeH.o HmNHHo.¢ HHvao.N HONHOO.H HHeveo.o Aomvmm.m Hmmvum.H HmHHmN.o -ngum5-o Lo -m-H>;Hm-~ .m:w~mcxm ANNHuzzv mcw~mcxm m Ammmvipxgumewcu .m:w~mcxm HmmmH-HH;Hach-m.~ .acHNMLHa HmomH-HH;Has .mcHNMLHa Hammvmc_~mcx¢ HmpoccxanzH A.u.u:ouv H mFQMH 160 Hmv Huccuxm Hams .ucmmmm_a:: MHH mmpnmum w> umxooo .xpxowm .mzogzmpzm Amy :o_co .UVchm .mzocaepzm mH .mcocum .NH.HH.oH Hca> mH Amy cowco NH.HH.oH .UHHLam HHH.NV mH.NH :couaoa -.oH HH.oH Hmv mmcwmcon .ucczn .xxosm HmHH HscHaz mm.HN.om NH.HH.oH .HHHsz Hmv axHH lucm>Hom .mp2: .uwucmc HHHcmHHm mN.HN.oN NH.HH.oH .HHHsz HNHHHN.N Amcvmo.o Hmmvmm.o HmHvam.H HHmHmN.o Hmevmo.o HoevHo.o Hmevuq.o -ngHaeHu .auHcHsmHo WQZDOQzOQ oszH HONH cogqsmu ago HHV ummzm .cmmcu HHH “cwmcza .HHHaHm Hmv xcmuuao .ucgsm Hmuv-- HNHH-- HHUH-- Hmmvme.o Hoevmo.o Hmmvmm.o HHevHH.o Ho¢H~o.o Hequo.o H¢V©N.o quvoe.o Hmmvom.H HmuH-- HNHH-- HHQH-- HoveH.N HHeva.o HqHHOH.o Amvmm.mH HHHWoo.o Hme Ho.N HmmvNH.¢ m>wum>wcwu cou_—wm m -HHHHHm upxgumewcavnm .uwum uwo~cmm -pzzumEmuuo .mcmxopwmmcuwpopuxu mhzgumE-H .mvwxocmaocux: "nocopsuwcu .mcmcumz H-A—xaoca -ngpwsumvum .mcwEmpxxocu»: wmc_sm_ccmaoca-~.H mnemzuoamHHz wszHHHmH=aHH .muuzuoca cwmpoca mom cw umucoamc xpmzow>mca camp as: m>m:H MommH .oaoEmnrgm ucm mmcwccmav xmucH mum>o¥c .H wczmwu cw mam; cameocgu m>HHumammc mzu co mcwcmnsac mxmmau .mucmccsnm ucwugma o>wumHmm HHmmHH .Ha Ha gaHmz .mm HHomHH .Ha Ha Hmc< .mN HommHH .Ha Ha HeHgagm .H HHmmHH .Ha Ha apex .em HcomHH .Ha Ha Hac< .NN HHmmHH HHHHaoc< HemoHH .Hm Ha oHcamoa .mm HmcmHH .Ha Ha HHaEHnsu .HN -cHaoaHxam new uoaHuaz .oH HommHH HeaHHaa .Nm HNNmHH .Ha Ha casxcHLm .om HmHmHV .Ha Ha mHHumm .m HefimHv sousm co> Gem HmH>o .Hm HmmmHH .Ha H6 or .mH HmmmHv uoaHuaz new maa< .m HmHmHH .Ha Ha cazou .om HmHmHH HeaEmHH new ccoHeo .mH HeomHH chaHom .H HmHmHH .Hm H6 can: .mm HNHmHH OHam new anmcmHmz .HH HemaHH aNscz new HaHHHa .m HHonHv .Ha Ha Hchaz .mm H¢mmHv coaHuaz new HHmo .oH HmmmHH mango use comLaHaa .m HmonHH .Ha Ha Hchaz .HN HHHmHH .Ha Ha Hmmnm:0H .mH HmHmHH .Hm Hm camcaHaa .e HHonHH .Ha Ha mcmHHHg .om HonHH LaHNHacm egg 0:6 .eH HonHH Huoaaou new aoaHumz .m HmonHH .Ha Ha meaHHHz .mN HNmmHH mae< new uoaHamz .mH HonHv .Ha Ha >om=acao .N HmmmHv .Ha Ha ammmm .em HHmmHV mae< ecu comHuaz .NH HmHmHH zoexm cc) new camcaHma .H ”mmucmcmwmmm H.G.Hcoav H mHnaH 163 Reconstructed ion current 3 . . . 3' IN 0 U) ‘< = l'? 37 __ I“? 23“ H. a S m m H rm ._;:::::::=EE=EEEEES H m 5 K2‘ U“ < . :1 9. E _ =2:- r—______H=s 'l“ A ————= —- EL __=b____HH_———==' w E (‘D ".i__.=-___ U'I V G- HH-=fim - fix: ‘ -a»~——___ g 551:2... \O m S... /f H 5‘ ~__;SL_____ ,. = 5°:- ‘3 l /w : FH_ H: N I n.._ k U) I 38 <2 I p—a v--- I Ln 9 I t—d : . o I u : l H N v’ ~,~_ to____.__o.__ B 3., _————————-———=—-————_ C N ‘ €;;::_53 m (c:: ‘ ) H:— 2 ,3 ‘3' H.- - N a 2" . : m U'I .>L. N or I r 1 ‘1‘ P .0 3|” '1"! I073 - Figure 1. Reconstructed ion chromatograms of the volatile isolates of (a) synthetic meat flavor (HH), (b) flavored soy extrudate (15HH), and (c) unflavored soy extrudate (UFC). See peaks identifica- tion in Table 1. S: solvent. 164 Reconstructed ion current a. 339.2. m3. mxnncamnm aux—C Ah 1m. Fm m6 No: mm. mm OH am am . F 2 .00 ”ac . :3 93 mxcmaama momwm #V ow mu I a 3.3 not. :3. :3 Figure 1 (cont'd.) 165 Reconstructed ion current O. HS :3 camHmmc oANV pom ofimv omzumcoz coon nczocm acoocom .mo>oo_ coon uczocm coxooo uco 3o; co mucopcoo poc uco oczumcoe mg» :0 mouovscuxm mow Ammmv umco>o_c:: uco Azzmfiv noco>opc cucz cocazucummzm mccmoococc co muooccm .N ocmoc 193 3o; cc a moofi x uoxooo cc N - 3o; cc N mo commocmxmm .Amo.ovav acococccu acucooccccmcm uo: oxo: mesapoo cc couuop oEom ozu mm oozopcoc moapo> .cocusucumnzmuzom co po>o_ zoom cccucz .mpozcoca 3o; oz» mamco> uoxooo on“ cc uczoc ocoz mucoucoo uoc cco oczumcos Amo.0vmv cozop x—ucooccccmcm .mo>oo_ coon nouaucumnzm momimom use -mmv cc mucmucoo poc ofi co :ocuamoxo o5 5c: .momboco 3823.5 co mcocuogou econcoummmcooa ocoz notoaoc mozco>o A.v.u:ouv N ocnoh 194 function in retention of fat, but do bind and retain moisture. The amount of fat lost during cooking depended upon the level of fat originally present in ground beef before cooking. Wolf (1970) explained that soy proteins are hydrophilic and would, therefore, be expected to absorb and retain water. Cooking Characteristics At all substitution levels, significant differences (p<0.05) in total cooking losses were observed between the all-beef (control) product and the soy-substituted beef loaves. However, no significant differences (p<0.05) were found between beef loaves substituted with flavored soy extrudate and those with unflavored soy extrudate (Table 3). The total cooking loss was determined as the combined total of drip and volatile losses. In general, the total cooking losses decreased with increasing level of soy-substitution, apparently leveling off at the 45% substi- tution (Table 3). Minimal drip losses were associated with the 45% and 60% soy-substituted beef loaves. The cooking drippings were reported to contain approximately 3.5% protein, 50.3% fat, and 45.2% moisture, for the 30% TSP-substituted beef patties by Kotula and Berry (1986). The volatile losses were attributed to losses in moisture and aroma volatiles (Williams and Zabik, 1975). The cooking yields were determined by difference and were positively affected by increasing level of soy-substitution (Table 3). Up to a 6% increase in yield was obtained with soy-substituted beef loaves as compared to the all-beef product (control). The results are in 195 Table 3. Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the cooking losses of ground beef loaves. Percent level Ground beef Cooking losses (%)a of soy: loaf SUbStItUtIO” Total Drip Volatile Yield (%)a 30 All-beef (Control) 13.2 4.7 8.5 86.8 «50.1b 10.2b :0.1b :0.1b Beef + 15HH 10.9c 0.4 10.5 89.1 :0.5 50.1C :0.4c :0.8C Beef + UFC 10.2 0.6 9.7 89.8 51.0c :0.3C 30.7c £0.4c 45 All-beef (Control) 13.3b 4.5b 8.8b 86.7b :0.2 :0.3 :0.1 :0.6 Beef + 15HH 7.2 <0.05c 7.2 92.8 50.5c :05C :04C Beef + UFC 7.9 <0.05C 7.9 92.1 50.4c :0.4c :0.3c 6O All-beef (Control) 13.6b 4.7b 8.9b 86.4b :0.1 :0.1 :0.1 10.1 Beef + 15HH 8.6 <0 05C 8.6b 91.4C :0.6C :0.6 :0.1 Beef + UFC 8.4 <0.05C 8.4 b 91.6 50.2C :0.2 :0.5C aValues reported were meanststandard deviations of triplicate analyses. Within each level of soy-substitution, values bearing the same letter in columns were not significantly different (p<0.01 . 196 agreement with those of Judge et al. (1974), Williams and Zabik (1975), Bowers and Engler (1975), Drake et al. (1975), Seideman et al. (1977), Ray et al. (1981), and Miles et al. (1984). Sensory Evaluation At the 30% substitution level, no significant differences in the sensory qualities (p<0.05) were found between the all-beef (control) and the soy-substituted beef loaves, except for juiciness (Table 4). Beef loaves substituted with 30% unflavored soy extrudate were signifi- cantly less juicy (p<0.05) than the control, but not significantly different (p<0.05) from those with the flavored extrudate. However, no significant differences in juiciness have been reported by other researchers who compared all-beef and beef/soy patties or loaves (Bowers and Engler, 1975; Williams and Zabik, 1975; Smith et al., 1976; Seideman et al., 1977; Gardze et al., 1979; Ziprin et al., 1981; Berry et al., 1985). At the 45% level of soy substitution, beef + UFC loaves were rated significantly lower (p<0.05) in aroma, flavor, juiciness, mouthfeel and overall acceptability than the control beef loaves. In contrast, beef + 15HH loaves were not significantly different (p<0.05) in the aroma, flavor, and juiciness ratings than those of the control, although they were rated significantly lower (p<0.05) in mouthfeel and overall acceptability. In comparing the flavored versus the unflavored soy-substituted beef loaves, the flavored products were significantly higher (p<0.05) in aroma and flavor. Substitution with soy extrudates at the 45% level did not significantly affect the color (p<0.05) of the 197 Table 4. Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the sensory ratingsa of ground beef loaves. Percent Ground beef loaf Sensory level of attribute soy- substitu- All-beef Beef + 15HH Beef + UFC tion (Control) Aroma 30 6.7:1.4b 5.811.6b 5 7:1.5b 45 6.8:1.2b 5.8:1.Sb 5.3115c 60 6.3:1.2P 5.3:1.5b 4751.5c Flavor 30 7.3.51.4b 6.0:1.6b 5.8:1.2b 45 7.3:1.2b 5.8:1.6P 4.8:1.6c 60 7,351.2b 4.7:4.7b 4.2:1.0c Juiciness 30 6.7:1.2b 6.0:1.4P’C 5.0:1.1C 45 6.711.65 * 6.0+1.7P’E 5.3:1.5g , 60 7.3:1.2 . 5.8:1.5¢: 5.7:1.0 ’ Mouthfeel 30 7 0:1.1b 6.3:1.2b 6.3:1.4b 45 7 5:1.3b * 6.011.3C * 6.011.4c * 6O 7 7:1.0b, 4.7:1.2C» 5.0:1.4Cr Color 30 6.5:1.5b 6.5:1.1b 6.0:1.3b 45 7.0:1.3B * 6.0:1.3: * 5.751.22 * 6O 6.8:1.5 , 6.0:1.1 . 4.8:1.5 , Overall 30 6.811.3b * 6.0:1.3b * 5.8:1.3b * Accepta— 45 7.251.2b’ 5.0:1.10: 4.5.1.5c. bility 60 7.2:1.7b 4.8:1.3c 4.0:1.1d aValues reported were the meanststandard deviations of the ratings of six panelists. The sensory attributes were rated on a 10-point scale where l-lacking or masked to 10-very full for aroma and flavor, 1-very dry to lO-very juice for juiciness, 1-very undesirable to 10-very desirable for mouthfeel and color, and 1-very poor to 10-very good for overall acceptability. Values followed by the same letter in rows were not significantly different (p<0.05 or p<0.01 as denoted by a * following the letter). 198 ground beef loaves. At the 60% level of soy substitution, beef loaves containing the soy extrudates were rated significantly lower in flavor (p<0.05), juiciness (p<0.01), and mouthfeel (p<0.01) than the all-beef product. While substitution with 60% flavored soy extrudate did not affect the aroma (p<0.05) and color (p<0.01) ratings of the ground beef loaves, substitution with the unflavored extrudate had a significant undesirable effect (p<0.05) on these attributes. Overall, beef loaves substituted with the flavored extrudate were rated more acceptable (p<0.05) than those containing the unflavored extrudate, but less acceptable (p<0.05) than the all-beef product. In general, the all-beef products received an average rating of 7 for all sensory attributes evaluated. They were characterized as being moderately juicy and having a full aroma and flavor, and as being moderately desirable in color/mouthfeel. In contrast, the soy- substituted beef loaves received an average sensory rating which decreased from 6 to 4 with increasing levels of soy-substitution. The soy-substituted ground beef loaves were generally described as being slightly dry and having a mealy mouthfeel, which intensified as the amount of soy added was increased. The juiciness and mouthfeel ratings of the ground beef loaves were highly dependent on the level of soy- substitution. Generally, beef + UFC loaves were perceived as being slightly dry, having a slightly weak aroma/flavor, and an undesirable color/mouthfeel. On the other hand, beef + 15HH loaves were described as being slightly dry, having a moderately full aroma but a slightly weak flavor, a moderately desirable color, and an undesirable mouthfeel. 199 The decrease in aroma and flavor ratings with increasing soy levels in ground beef patties has been reported by other researchers (Bowers and Engler, 1975; Gardze et al., 1979; Seideman et al., 1977). Seideman et al. (1977) also reported that the addition of TSP in excess of 10% was associated with light-colored, less desirable patties. Oxidative Stability Substitution with soy extrudates significantly increased (p<0.05) the oxidative stability of cooked ground beef loaves during refrigerated storage (m4OC) for 6 days (Figure la-c) when compared to the all-beef products. This observation agrees well with those of Bowers and Engler (1975), Seideman et al. (1977), Thompson et al. (1978), and Ray et al. (1981). However, there were no significant differences (p<0.05) in the oxidative stability between beef + UFC and beef + 15HH loaves at all substitution levels. The TBA values increased significantly (p<0.05) for the all-beef product (control) and the 30% soy-substituted beef loaves at day 2 of refrigerated storage (m40C) as was reported by Williams and Zabik (1975). At the 45% and 60% substitution level, storage time had no significant effect (p<0.05) on the TBA values of soy-substituted beef loaves. Ray et al. (1981) also reported that storage time (0 to 10 days, at 00C) had no significant effect on the TBA numbers of soy- substituted (up to 26%) beef patties. Some irregularities in the TBA storage data were observed for soy- substituted beef loaves. This "zig-zag" effect has appeared in several publications (Williams and Zabik, 1975; Seideman et al., 1977; Thompson 200 TBAnmubu g 8 TBAnumbov ‘3 E. i. .1 g 2 a 3 .3 E «T- 3 l g a! 3 1% a... 'flAnum :- 0.4 g 9 2 a 3 t z ; - 1V Ml "‘ '° 3 GI r. z 3‘ II: ‘5' 8 §£ 5 ‘1 3 0 g g 1". E g. .1! g , y 2 :§4 3E Figure 1. Effects of increasing substitution with flavored (15HH) and unflavored (UFC) soy extrudates on the TBA numbers of ground beef loaves stored at m4°C for up to 6 days. 201 et al., 1978; Ray et al., 1981). Although no obvious explanations are evident, some plausible explanations may include: (a) unaccounted moisture loss during storage, (b) presence of interferring compounds derived from non-enzymatic browning reactions, and (c) binding of malonaldehyde to soy proteins. More definitive analyses such as hexanal measurement are needed to support TBA data in the quantitation of lipid oxidation in beef/soy systems. Although the phenolic antioxidative activity in soy protein products has well been established (Pratt, 1972; Hayes et al., 1977; Pratt and Birac, 1979; Pratt et al., 1981), one may speculate that the decrease in malonaldehyde concentration was, in part, the result of lower fat contents in the soy-substituted beef loaves (Bowers and Engler, 1975; Ray et al., 1981). Maillard reaction products between amino acids and reducing sugars have also been shown to possess anti- oxidative prOperties in model systems (Lingnert and Eriksson, 1981), and may be involved in improving the oxidative stability of the soy- substituted products. However, these effects were not observed in beef + 15HH loaves. CONCLUSIONS Increasing substitution (30 to 60%) with the flavored soy extrudate had no significant effect on the raw and cooked composition (% moisture and % fat), cooking characteristics (% total cooking, drip and volatile losses), and oxidative stability of ground beef loaves as compared to those containing the unflavored soy extrudate. In contrast, substitu- tion with soy extrudates at levels of 30 to 60%, irrespective of whether flavored or unflavored extrudates were used, resulted in higher moisture and lower fat products with reduced cooking losses and enhanced oxidative stability as compared to the all-beef product (control). Sensory data indicated that increasing substitution with flavored soy extrudate had a significantly positive effect on aroma and color, but a limited effect on the flavor of ground beef loaves in comparison to those containing the unflavored extrudate. At increasing levels of soy-substitution, ground beef loaves substituted with the flavored soy extrudate were generally more acceptable than those containing the unflavored extrudate, but less acceptable than the all-beef product. The sensory attributes (juiciness and mouthfeel) of ground beef loaves were significantly affected by increasing soy-substitution, and conceivably, may have strongly influenced the overall acceptability SCOY‘ES . 202 203 In conclusion, pre-extrusion addition of meat flavor precursors in soy extrudates has the definite potential in improving the flavor of SPPs for use as meat extenders or analogs. Therefore, innovative research efforts should be continued in this area. REFERENCES Berry, B.W., Leddy, K.F., and Bodwell, C.E. 1985. Sensory character- istics, shear values, and cooking properties of ground beef patties extended with iron and zinc-fortified soy isolate, concentrate or flour. J. Food Sci. 50:1556. Bowers, J.A. and Engler, P. 1975. Freshly cooked and cooked frozen reheated beef and beef-soy patties. J. Food Sci. 40:624. Drake, S.R., Hinnergardt, L.C., Kluter, R.H., and Prell, P.A. 1975. Beef patties: Effect of textured soy protein and fat levels on quality and acceptability. J. Food Sci. 40:1065. Funk, K., Aldrich, P.J., and Irimiter, T.F. 1966. Delayed service cookery of loin cuts of beef. J. Am. Diet. Assoc. 48:210. Gardze, C., Bowers, J.A., and Caul, J.F. 1979. Effect of salt and textured soy level on sensory characteristics of beef patties. J. Food Sci. 44:460. Hayes, R.E., Bookwalters, G.N., and Bagley, E.B. 1977. Antioxidant activity of soybean flour and derivatives - A review. J. Food Sci. 42:1527. Hsieh, Y.P.C., Pearson, A.M., and Magee, W.T. 1980. Development of a synthetic meat flavor mixture by using surface response methodology. J. Food Sci. 45:1125. Judge, M.D., Haugh, C.G., Zachariah, G.L., Parmalee, C.E., and Pyle, R.L. 1974. Soy additives in beef patties. J. Food Sci. 39:137. Kotula, A.W. and Berry, B.W. 1986. Addition of soy proteins to meat products. In "Plant Proteins, Applications, Biological Effects and Chemistry," R.L. Ory (Ed.), p. 74. American Chemical Society, Washington, DC. Langsdorf, A.J. 1981. Economics of soy protein products and outlook. J. Am. Oil Chem. Soc. 58:338. Lingnert, H. and Ericksson, C.E. 1981. Antioxidative Maillard reaction products. 1. Products from sugars and free amino acids. J. Food Process. Preserv. 4:161. 204 205 Miles, C.W., Ziyad, J., Bodwell, C.E., and Steele, P.D. 1984. True and apparent retention of nutrients in hamburger patties made from beef or beef extended with three different soy proteins. J. Food Sci. 49:1167. Nofal, M. 1981. Effect of textured soy flour level on the acceptance of ground beef in Egypt. J. Food Sci. 46:1630. Pratt, D.E. 1972. Water soluble antioxidant activity in soybeans. J. Food Sci. 37:322. Pratt, D.E. and Birac, P.M. 1979. Source of antioxidant activity of soybeans and soy products. J. Food Sci. 44:1720. Pratt, D.E., Pietro, C.D., Porter, W.L., Giffee, J.W. 1981. Phenolic antioxidants of soy protein hydrolysates. J. Food Sci. 47:24. Ray, F.K., Parrett, N.A., Van Stavern, B.D., and Ockerman, H.W. 1981. Effect of soy level and storage time on the quality characteristics of ground beef patties. J. Food Sci. 46:1663. Schweiger, R.G. 1974. Soy protein concentrates and isolates in comminuted meat systems. J. Am. Oil Chem. Soc. 51:192a. Seideman, S.C., Smith, G.C., and Carpenter, Z.L. 1977. Addition of textured soy protein and mechanically deboned beef to ground beef formulations. J. Food Sci. 42:197. Smith, G.C., Marshall, W.H., Carpenter, Z.L., Branson, R.E., and Meinke, W.W. 1976. Textured soy proteins for use in blended ground beef patties. J. Food Sci. 41:1148. Tarladgis, B.G., Watts, B.M., Younathan, M.T., and Dugan, L.R. 1960. A distillation method for the quantitative determination of malonaldehyde in rancid foods. J. Am. Oil Chem. Soc. 37:44. Thompson, S.G., Ockerman, H.W., Cahill, V.R., and Plimpton, R.F. 1978. Effect of soy protein flakes and added water on microbial growth (total counts, coliforms, proteolytic, staphylococci) and rancidity in fresh ground beef. J. Food Sci. 43:289. Whipples, C. 1974. Quality characteristics of soy-substituted ground beef, pork, and turkey systems. M.S. Thesis, Michigan State University. East Lansing, MI. Williams, C.W. and Zabik, M.E. 1975. Quality characteristics of soy- substituted ground beef, pork, and turkey meat loaves. J. Food Sci. 40:502. Witte, V.C., Krause, G.F., and Bailey, M.E. 1970. A new extraction method for determining 2-thiobarbituric acid values of pork and beef during storage. J. Food Sci. 35:582. 206 Wolf, W.J. 1970. Soybean proteins: Their functional, chemical, and physical properties. J. Agric. Food Chem. 18:969. Ziprin, J.A., Rhee, K.S., Carpenter, Z.L., Hostetler, R.L., Terrell, R.N., and Rhee, K.C. 1981. Glandless cottonseed, peanut, and soy protein ingredients in ground beef patties: Effects on rancidity and other quality factors. J. Food Sci. 46:58. (a) SUMMARY AND CONCLUSIONS The major conclusions from these studies are as follows: The meaty aromas thermally generated from the synthetic mixtures of meat flavor precursors were superior to those of the commercial flavor samples and comparable to that of the natural beef extract. Toasted/burnt, sulfurous, and cooked vegetables-like nonmeaty aroma qualities were frequently identified with the synthetic flavor mixtures. The pre-extrusion addition of flavor precursors effected a moderate but significant improvement in the meaty flavor of extruded soy protein products. However, under the existing extrusion conditions, the flavor precursor system was not entirely successful in masking the typical green/beany off-flavors of soy protein products. Generation of several new heterocyclics (pyrazines, furanoid compounds, and thiazole) and substantial increases of 2-pentanone, dimethyltrisulfide, and the Strecker aldehydes of leucine and isoleucine, were evident in the soy extrudate pre-extrusionally added with meat flavor precursors. These compounds may have significant implications to the meaty flavor perceived in the extrudate. Increased level of substitution (30 to 60%) of the flavored soy extrudate (15HH) had a significantly positive effect on the aroma 207 208 and color but a limited effect on the flavor of ground beef loaves. The juiciness and mouthfeel of the products were adversely affected by increasing levels of soy-substitution regardless of whether flavored (15HH) or unflavored (UFC) soy extrudate was used. Overall, all soy-substituted beef loaves had higher cooking yields, lower fat, and enhanced oxidative stability. FUTURE RESEARCH From the results of the studies on meat flavor generation in extruded soy protein products, the following future research is suggested: (a) More discriminatory testing should be carried out to monitor meat flavor development under varying combinations of precursor formulations and extrusion conditions. Varying combination levels of sulfur-containing meat flavor precursors (hydrogen sulfide, cysteine, methionine, taurine, thiamine), amino-containing compounds (glycine, B-alanine, aspartic and glutamic acids, lysine, histidine, proline, and 5'-nucleotides), and sugar/ carbonyl compounds (arabinose, glucose, fructose, ribose, xylose, ribose-S-phosphate) should be investigated. Surface response methodology may prove to be an invaluable tool. Due to the short residence time encountered in the extruder, the reactivity of the meat flavor precursors is of primary consideration. Alternately, the use of microencapsulated Maillard reaction meat flavors should be investigated. Microencapsulation offers the advantages of preventing or minimizing (a) soy flavor-protein interactions, (b) thermal degradation of flavor compounds, and possibly (c) steam volatilization of flavor compounds at the exit port of an extruder. 209 210 Due to the extensive information generated in the area of Maillard reactions and their products, research efforts should be expended in constructing a computerized database for storing, ease of retrieving, and cross referencing of the literature data. APPENDIX APPENDIX MASS SPECTRA OF SOME MEAT FLAVOR VOLATILES 211 RELATIVE INTENSITY, % .50 mo um VIOV>Z>P olozoo at am filllfl J... a. +— a q» -o .0 u—p 1)- cl)— 1h W— U! 4 3} we Animus-O)? Z>im 30506;! $5014 Ding-0).: “0336...) ICK) 212 RELATIVE INTENSITY, % 8' I ‘3 FURAN c,H,o lawns q q oIIIFIIrf'IFIrIiIUrTIVIUIUllrIIITTTITTIU] 40 43 50 55 60 65 70 75 80 we ICXJ ‘3 2-BUTANONE 7 c,w,ouw72 59 .. E a) . 2! I‘.’ 55°“ 11: a . '- 72 5 (“:1 d 57 0 Al I 1 1 Ill 1 L IWIIIITII IIIIIIIIIIIITIII I [IllllTI 40 45 so 55 60 65 78 75 ea 213 100 _ ‘3 2 - umvmoemm cwwouwn * ‘ a d 2 Lu .- E 50- m 2 3 -4 m m a J A O ,4 1 III I 11 ITIUI TIEIIIITTIfTIIlIrrrIIITUIIITr] 4O 45 50 55 60 65 70 75 88 m/e 100 wmzme 3" I c,w,w,uweo 2:. _ 53 a 4 2 E 5 5°“ In a _ '5 m —l I: o 55‘ [TTTiIT ILIITIEI—TIITTIII rII‘IIffilFrjllirIl 40 45 50 55 60 65 70 75 80 85 99 m/e 1C!) RELATIVE INTENSITY, 96 8 ICXJ IRIELJ\11\IEEIII11EIIEBITIL 96 214 . THIOPHENE 3‘ c,w,s uwea 58 ‘ 45 II J 1 11,1 1 I I l I l I I] I ILL, I I 1 I I I I I I l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 49 45 50 55 60 65 7O 75 80 85 90 we 43 5? 2, 3 - BUTANDIONE . c,II,,o2 uwea . 86 l I l 1 - L l I L A - g A L I I I I I I T I I I I I I I I I I—I I I I I I I I III I_I I r1 I I I I Iv—I—I'T I I I 40 45 59 55 68 65 70 75 80 85 90 ODD“! 215 1C!) 57 CYCLOPENTANOL csumo was RELATIVE INTENSITY, 96 8 I ‘4 86 O IIIITITIILHIIiTLIT‘ITT‘ITITIILTLIITIIIfiTTTITITIILIILIr] 4. 05 5' 55 6. 55 7. 75 5. 85 9. W0 1C!) 57 I-PENTEN'3°OL ‘ csuwouwao Be - X4 E F U) .1 :5 E‘.‘ 55°“ MI 5’ . I: 5 g ‘ ‘4 I 0 [till -mn.l.lj II . 11- I ll , TIITIIIII TFTFII TT lIrT IIII IIIIIIIIIIIIII 11TTI 4. 45 5. 55 55 65 75 75 8. 85 90 THUG! 100 216 RELATIVE INTENSITY, 96 8 l 45 a - NYoRoxvaIITAN - 2 . ONE c,II,,o2 uwaa X2 O I! l ITTIIrriIIIIIT TTfigITITITTIIIIrTrITITTI II 40 45 55 55 5. 55 7C 75 8° 85 ” III/O 100 42 55 1-PENTANOL ' c,w,,ouwaa 3 _ F) ‘ n z E 55“ III a . '5 m d m | 0 II II I I] L JL 1 11 ITIITIIIII IIITIITrT IIII IIIIIIIIIIIIIIIFIIT‘I 4. 45 5. 55 5. 65 75 75 3. 85 90 100 RELATIVE INTENSITY, 96 8 100 a? >: L'. In 2 E 550 III 2 '5 III I: O 217 m/e METHYL bIsULFIoE 9‘ ‘ c,w,s,uwu 79 .. 45 cl " 61 III! IIIIIIIIIIIIIIIIIIIIT—I—IIIIIIIII iIlIIIIIIIII—IIILIIIII‘I 4O 45 50 55 60 65 70 75 80 85 3 95 I” we 2 - METHYLPYRAZINE 9‘ c5R3N2Mwu ‘1 67 I 53 42 I :1 L -IIIP Lllll . l IIIIIIrIIITIIIIIIIIIIIIIII II IIII IIIIIIIIIIIIIIIIII IIIIII 4O 45 50 55 68 65 7O 75 80 85 90 95 100 218 TRANS - 2 - HEXENAL C.Hmo aw on 83 69 III Ij—II II IIIITIIIIIIIIIII l I 95 85 I. 76 we III I . .llll I IIIIIIIIIII 65 55 I I I ...II.H | .- ml IIITIIIII 50 5 l. 40 100 . q _ a . m cm .t.m2m._.z_ m>_._.<...mm q 0 97 ! 2 - METHYLTHIOPHENE c,n,s NM 98 45 Ill llllll 111.11.] .III rTrT 5 IIII ll: ,1] IIIIIIIIIIIIIIII 90 L IIIIIFIIIIIIIIIIIIIIIIIII L3". 1 95 85 75 7O 65 60 5 | 4 4O 100 — 1 q d — m g. fazmhz. nation 0 219 HEXANAL c,H,,o MW 100 , A IIIIIIIIIIIIIIIITIIII A.‘ A AA A A IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIII 45 LN I 100 A] d — a - Ax. Sta—‘95: m>....<._m¢ O I 95 ID. 105 110 9 85 “6570758. We 55 40 2 - HEXANONE conuo law 100 100 X2 J 58 43 ‘A A II IIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIhIIIIITIIIIIIIIIIIIIIr « d _ 4 _ _ w e. .cEmzocz. making 100 0 80 85 90 95 100 195 I 10 75 5 40 220 100 57 a-NEXANONE 43 C.M,,ouwmo * i a 71 2 'l III I- E 50. III 2 E ‘ 100 Ill 3 A O I l l . 1.Il I1 I I II 1 II IIIIII‘IIIIIII II [III III—I IIW IIIIIIIII IIIIII—rIIIIIII IIII IIII 40 45 50 55 6O 65 7B 75 89 85 90 95 100 105 110 W0 100 57 CIs-z-RexEN-i-OL C.M,,ouwmo $ q >: ': m .4 Z l‘.‘ 5 5°‘ III 2 ~ 67 3 .2 In .4 I O I! IITITTiI‘FIIll! IIIITTI I III—IITIITIIIIIIIIIIIIIIIIIIIIIII 4O 45 59 55 60 65 7O 75 89 85 9O 95 IO! 221 100 57 4 - METHYL- 2 - PENTANONE c,R,,o now 100 L 43 7‘ 100 RELATIVE INTENSITY, 96 8 l ! ! .. ll . 1 , 1 IIIIII IIII IIII IIIIIIIIIIIITIIIIIIIIIIIIIIII IIIII 49 45 59 5 69 65 79 75 89 85 99 95 99 I95 I 18 m/e 100 55 7- VALEROLACTONE ‘ (251-1702 MVHOO 59 -i 85 >: L'. a, 4 E 43 I- ! 50‘ III 2 4 '3 g 7 we 0 [r IlIIIIIIIII! IIIIIII IILIIIIIII.IIII IIII IIIIIIITIIIIIIIIIIIIIIIII 49 45 58 55 69 65 78 75 89 85 99 95 I99 195 119 100 222 RELATIVE INTENSITY, 96 8 1 43 5‘ 1 - HEXANOL ' C.H“O MW 102 X4 69 84 o TIIIIIIII II rIIIIrII IfIIIIIII‘IIrlIIIIIrIIrIIIII IIII IIIII 48 45 55 68 65 78 75 88 85 98 95 1“ I85 118 m/e 100 STYRENE 13“ ‘ cauanvnm 59 i t“ 78 a . 2 E 5 5°‘ III a . I- 5 51 m - I: o 111; Al lo-ll . I llll LIIAJJJI I; ll LL ALA-l J- IIIIIIIII IIII IIII I_III IIIIIIIIIII IIIIII IIIIIIIII IIIIIII IIIITI 48 45 L8 55 68 65 78 75 88 85 99 95 I88 I85 I I9 223 100 RELATIVE INTENSITY, 96 8 I 51 77 SENZALDEHYDE c.,H,o MW 108 —. ‘- (l .6 I75lTlrr”TTITTTTITTITITTTTIITTI 95 I88 -_ II8 100 RELATIVE INTENSITY, % 2 - ETHYLBENZENE can", law 106 91 186 Ill 75 88 85 l. IIIII TTTT 98 IIIIIIII IIII 95 I88 II I85 118 100 224 RELATIVE INTENSITY, 96 8 I 53 2 . ETI-IYLPYRAzINE “7 C.H.Nz uwwa 89 0 II.- -I I IlLl-- -- A - - I-, - I IIIIIITTI I IIIIIIIIIIIII IIII IIII IIII IIIIIIIII IIIIIIIII I II 49 45 59 55 69 65 79 75 99 85 99 95 199 195 119 m/e 100 81 t, t- 2, 4 - HEP‘I‘ADIENAL c7I-I,oouwno 59 ‘1 a -l 2 .‘E 5 5°“ g g 53 I- 5 118 m - 67 n: 0 [AI- .6:1;II. IAJL I--_ ,l- -l _ .I 2 . IIIIIIIII II IIITII IIITI ITITI IIII LIIIII TII IIIIIIIII IIIIIIIIT IIII IIITIIIII 49 45 9 55175 I89 95 99 95 I99 195 119 115 129 m/e ICK) ICNJ RELATIVE INTENSITY, % 225 RELATIVE INTENSITY, % 8 I I2 l 67 2. 3 - DIMETHYLPYRAZINE Coflaflz uwme 85 90 - Al II IIIIIIIIIIIIII II'IIIrIIIIS;TIIIIIII‘III 95 50 42 2, 5 - or 2, 6 - DIMETHYLPYRAZINE C.HBNz MWIOB ~— 45 59 55 I""l"”l II IIIIIIIII IIIIIIIT IIITIIIII 85 90 95 ml: 17" 226 2, 4, 5 - TRIMETHYLOXAZOLE c,H,No MW 1 1 1 III 195 119 115 129 l 35 90 ITII IIIIIIIIIIII I IIIIIIIIIIIIIIIIIIIIIIITIIIIIIIrIIIIUIII TIIIIITII ICXJ s 8 L I u I n l I a 7 I a IL 1 5 6 a 6 J 5 «u 5 l 1 l I o 1m 3 r. 5 ‘. [I4 I o ‘ u — d — q — O 90 .>.—._m2m._.2. m>_._.<._mm m/e 1 - OCTENE 79 can" awn: II 15 IIII FILLT I I 5 112 III II IO. 30 95 83 III IIIIIIIIIIIIIIIIIIIII 99 95 m/e L;III lrll ?I 65 IIIIIIIIIIII 55 5 I TIIITIIIIII I 40 I00 50 O ow .>._..m2m._.2_ m>:.<._mm HEPTANAL C.,H“o law 114 227 7a 1 115 114 TIIIIITIIIIIIII II. L5 1“ 2 - HEPTANONE C.,H“O MW114 99 96 95 85 85 ITILII Bl "mums. m/e X 4 l 111 L lllJln Lillllll 71 11111 11 It 53 IIIIII 6. 105 110 115 129 100 90 85 75 78 IIIIIIIIIIIrlrIIIlIIIIlITIIIIrrIlIIIIlIIIIIIIIIlIIII] 60 1 55 IIIT .1 1|” L. 45 43 50 45 4 l AIL AA A II IIIIIIIIIIIIII IIIIIIIII 40 1(K) ax. .>._..m2m.rz. m>_._.<4m¢ .x. .>._..w2m._.2_ m>.._.<._m¢ O RELATIVE INTENSITY, % RELATIVE INTENSITY, % 228 ‘3 5 - METHYL- 2 - HEXANONE c,u,4o raw 1 14 -< X4 " 58 .4 31 7‘ 114 l [L L .1 1.11[ l. A . A. 1 l I _ |_l _ II IlIIIITIIIIlII IIIIIIIIIII IIIIIIIIIIIIII I—rII ITTIIIIII IIII IIII IIIIIIIII 4O 45 50 55 60 65 7O 75 80 85 90 35 I00 195 110 115 IZB m/e '5 n-ocnus " c3H,,MW114 _‘ 43 57 71 .4 I" .4 fi ll- Al-ll I .-1 . .LA A L n I I II'lIIII IIIIrIIlIIII IIIIIIIIIIIII IIIIIIIIIIIIIIIIIITIIIITI11IIIII 4. 45 5. 55 6. 65 75 75 8. 135 9. 35 I“ I55 III 115 120 m/e RELATIVE INTENSITY, % RELATIVE INTENSITY, % 229 100 7’ 1-HEP‘I’ANOL ' c,H,,OMW11o _‘ 55 50-1 0 linrrlnI! filnnihl IIILIIIIIIIIIIIIITITIIIIIIIIIIIIIIIIIITIIIIII+II 4O 45 55 55 55 75 80 85 55 35 I“ 195 IIU 115 120 III/O 100 4 - METHYLSTYRENE “7 C.HwMWHB 50" 91 ~ 55 193 51 .III. , I‘ll—I l JJJIIIL 111-111 A: . 1 -,- - l- o TWI IIIIIIIIIQIIIIIIIIIIIIILIIIIu'T'TITIIIIIIII III IIIIJIIII IIIIJIIII I I IIII IIIIJ 45 45 55 5. 65 5 8. 55 95 95 u 135 I. I15 I25 125 3' m/e 100 100 RELATIVE INTENSITY, % 230 RELATIVE INTENSITY, % 8 l 91 mowusuzeue C91112 1111111120 120 1- 11-1 , 1.- LL 1 IIIIlIIIIlITIII T‘IIIII'IIIIIIIIIIIIIIIIIIIIIi 5. 5. 85 5. 556.657'75 -1, .1I 11 1 I we 1. 2, 4 - mmmvmenzeue cw,2 111w 120 91 129 III 1- 11 TTII IIIII 4.4550556865707580 I I , 1 , , IIII nn nrr ITII nu I I I I 30 95 III 105 II 15 120 125 I3. 231 [II I I I 5 I 2 ,III I I I I .I II .1 «1. III I r r I I 11 ,1!!! Re I DO 1 u [I I E 11 m .1.» 1 z I W. m 5 9 I m 1 I Y 1 1" .II’ a” II I M i '1 I 5 T I o M n 3 2 I ” 2.H1 I1I I Q. a II“ i 1.39 n” 1I K9 InII? I. .n I n. I? I I I AI Ill“ A. 1' LI 1.Ia LI LI I I ,5g 5 Ir II II 15” I I r 5 III4 j' I L1 I I 4 q q 5 q a _ a 100 .x. .>._..mzm._.2. wank-Em 185 120 125 130 120 I [-1 I 115 105 1 , 2, 5 - TRIMETHYLBENZENE c91112 MW120 9! 78 “I A‘ II -111 l. , lIIIIlIIIIIIIIIl Irnltr Hirrrnllnl IIIIIIIII' III 95 IO. 85 51 I58. 1,1111 1 I 65 55 50 1 '11.; ll-111 .. 111111 lnrlnn "IF "I” I 1111 45 100 3 .>._._m2m._.z_ Hakim". 4. O 232 RELATIVE INTENSITY, % 77 ACETOPHENONE cause 111m 120 195 128 I I RELATIVE INTENSITY, % II III II 1 14 l 7 IlIIII III II IIIITIIIIIIIIIIII IIIIIIITI III IIII IIII ITII IIII 65 7O 75 80 85 30 95 100 105 110115 120 125 138 we 91 PHENYLACETALDEHYDE cauaonwno 65 129 1 .I.-1- --- In I1 . -1 , 1 _ , IIIIIIIII IIIIIIIIIIIIIT] III'IIIIIIIIIIIIII IIII IIII IIII IIIT 70 I5 80 85 90 95 100 I05 III 115 120 125 I}! We 233 100 ‘2 2, 3, 5 - mmemvmmme c7150":2 awn: neumvs INTENSITY, % 8 1 122 81 4 54 o I IIT'IIIIIIIIIanIIIIIIIITIIIIIII;IIIIII III IIIIIIIIIIIIIIIIIIIIIIIIIIIIIT IITTI II IIII 40 45 5. 55 53 65 70 8. 90 95 I“ 105 110 115 129 I25 I30 m/se 100 2-ACETYLTHIOPHENE "1 ' couaosuwuo 59 d xxo a .. 55 Z 70 E 5 5°“ N 83 a 1 '3 I“ -1 cc ’7 1 o [14. I11-“ . JII 1-11 1 1| 1..“ II 7 I II ITI I II IIII III IIII IIIIIII IIIIITI' TI'IIIII IIIII ITIrI IIII II IIII IIII IIII 40 45 50 55 68 65 II 75 BO 85 30 '35 100185 110115120 I25 130 m/e 234 100 NAPHTHALENE m emu, aw 123 RELATIVE INTENSITY, % S 1 I02 II: P I...I.. III IIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII II I-III III 0 -u. IIII IIIIIIIIIIIIIIIIIIII I I""I "I 4O 45 50 55 60 65 7O 75 90 95 I" 105 III I15 I20 125 I30 I35 I“ we 100 57 n-NONANE ‘ cgumuwms 52 T E q as a) 2 I3 E 71 E 50 m a . ’5 III " 99 m I28 0 II A Illllll . 1.1 l A L I I , II; In I IIIIIILLIIIL; IIIIIIIIIII mLIIIIIIIII IIIIIIIIIIIIIII IIIIII rIIII IIIIIIIIIIIIIIII IIII III 40 45 SI 65 7B 5 80 I35 90 95100105118115120I25130 m/e 235 RELATIVE INTENSITY, % ‘3 57 OCTANAL C.H“O mu 1 28 X 4 63 84 109 RELATIVE INTENSITY, % IIII‘IIII ”infii! IlllllI? IIIII IIIIIIIIIIIIIIIII'IIIIIIIIIIIIIIIIIIIIIIIIIIIIhI 4. 45 L 55 5. 65 7. L5 8. 9' 95 I” 105 II. II5 120 I25 I30 m/e ‘3 2-OCTANONE 58 c,n,,o MW 123 X 4 128 71 113 I. I - - L - I I , II IITI IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIII IIII IIII B 75 80 85 99 95 100 185 110 IIS 120 125 138 We 236 100 A 43 2, 2, 5, 5 - TETRAMETHYLTETRAHYDMFURAN caH1 .0 MW 1 28 33 I7) 2 d I'.‘ 5 so - '55 7" “I 2 Es ~ 113 “I I: -I 95 I I () II IIIIIIIIIII IIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIITIIII I IIIIIIIIIIIIII 40 I5 5' 55 60 65 70 75 0. 85 9. 95 100 I05 IIO II5 120 I25 I30 W. 100 55 I-CNITARNDL I 7. C.M,.O MW 130 5CI‘ 04 RELATIVE INTENSITY, % IIIIIIIIIII IIIIIIIII TI‘ IIIIIIIT [IIIIIIIIIIIIIIIIIII IIII‘IIIIIIIIIIIIIIIIIII 40 45 50 55 60 65 70 75 00 90 35 100105 110115 I20 125130 as m/e 237 100 4 4-ETHYLBENZALDEHYDE 133 C9H1OOMW134 a? E: 91 105 In a -< I- 77 E 50., III 2 '5 ‘ 51 III 65 I: H m I I 0 II‘! I‘I‘l IIILI TT‘IW‘I I III”! i‘T ILI‘IlII' I I I I. ‘II Tl‘rl I I I III I I I rIlI III 40 I50 60 70 00 30 I00 110 I20 I30 I40 m/o 100 ‘3 2 - ACETYL- 3 - METHYLPYRAZINE ‘ 34 c,II,I~I,o IIIWIso 39 -I 136 IT: 1 2 III N 1 a q as '5 m _ 108 I: o I All . .1111 II I- . 1 A -1 I I I IIIIIIII IIIIIIIIIIII IIIIIII II IIII IIII II IIIIIIIIIIIIIIIIIIIIIIIIIII II IIII III I 40 45 50 55 60 65 70 75 00 05 90 95 100 I05 110 115 120 125 I30 I35 I40 m/e RELATIVE INTENSITY, % RELATIVE INTENSITY, % ICXD ICXD 50 238 2 - ETHYL- 3, s - DIMETHYLPYRAZINE ‘35 " cal-I1,”2 MW136 42 55 108 67 I IIIIIIIIIIIIIIII IIIIVIIIII! IIIIIIIIIIIIIIITIIITII IIIII IIIII IIIII IIIl IIIIII IIIII IIII IIIITIIIII III 40 45 50 55 60 65 70 75 00 05190195 I00 105 110 I15 120 125 I30 I35 I40 III/e I35 2 - ETHYL - a. a - DIMETHYLPYRAZINE Conn", MW136 56 ‘42 108 d 67 I II‘TTIIIIIIIJ IIIAIIIIIIIIIIITIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII I‘ 40 45 50 55 50 65 70 75 00 85 90 95 100 105 110 I15 120 125 I30 I35 I40 m/e RELATIVE INTENSITY, % RELATIVE INTENSITY, % 100 54 2, 3. s - TETRAMETHYLPYRAZINE ‘ Carina, mouse 7 136 ‘ 42 50 —4 I 1 LA - An; A - - 7 1.. I I o I I I”! IITIIIIIT I"! IIIIIIIII I"! 1111 I”! I1IIIIIIIIIITIIIIIIIIIIIIITIIIIIIIII" I 40 45 so 55 so 65 75 so 85 so 95 100 105 no 115 m 125 13a- 135 m two 100 . 57 n-DECANE emu“, uwuz ‘ 71 q a 85 50 -4 .J ‘ 142 as o TrTIIl I TITJI TITTITIIT‘IFFT IIIITIIJTIIIIIIII—TIITIIITT 40 50 60 70 80 90 IO. 11! 129 130 140 150 239 1CX) 1C!) RELATIVE INTENSITY, % 240 RELATIVE INTENSITY, % 8 l NONANAL C.M,,o now 142 X 4 82 43 "'::AT"r‘? i‘ltlt‘l‘t itl;7lliirrlifl 80 9. 18. 11. 129 130 140 we 2-NONANONE C9H1BOMW142 X4 142 99 Ill]: 1 l 1 #L 1 L IIIIIIIrIlIIIIIIrIIIITIIIfIIr ITIr 9 99 100 110 120 139 HO 1C!) 241 RELATIVE INTENSITY, % 8 l 1 - METHYLNAPHTHALENE c11 Hm law 142 115 142 O liIIiIIII! 41;]!Tgll‘!llrlTlll‘:l:li‘lIF;TITTI 11:1rrITTTTlTTT‘Tli TIT 4. 5' 60 7. 8. 9. la. 11. 12. 13' 14. 15‘ W9 1CX) 55 1-NONANOL " C.M,OOMWIM a? - ‘3 7o 7’ ‘ s3 2: E 5 5°“ g - d 97 3 111 m —I m I 0 ll 1;. Inll 11 A -All I. . A I ll 1. , .11 [A A, l , l .-- A ITTITI IIIIII ITIIII TTlITIIlITIT ITTI TTTr IIIIIIIIII 40 50 60 70 8. 3. 100 110 123 130 140 150 242 100 2 - METHYLTHIO - a - ETHYLPYRAZINE 15‘ ‘ gamuas uw154 121 * cl E 133 m -1 2 III I- E 504 III > C J 52 84 3 a: - 95 0 l!‘!|!|§‘il ILJUTITWJLTHI!LIIJLlg IL] I THLILi T 1’“!th T T l! #TLJT I T I]! III I I r I r I! I 40 50 60 7O 80 90 I“ 1110 112. 1'3! 1'4. 150 1160 m/e 100 DECANAL ‘ 57 67 82 cmumo MW156 8 .4 E w d 2 E 4 E 50 96 3 J l- 5 112 E ‘ 123 o A lll .l 11 I'll]: _ 1 l L 11,1 L 1 . [TTFL‘IIIIIIII l‘l'l lirlli IIIIIIIIUIUIFTII ITIWIYUI'IIIITI 4O 68 I! B. 9. I” III 120 138 I“ 150 60 100 RELATIVE INTENSITY, % 8 100 RELATIVE INTENSITY, % 8 243 ‘3 53 2-DECANONE ‘ ch-Imouwwo " X 4 71 156 .1 141 111T1‘ill1l11‘F‘Til1lilitlll1l1l1ilIIIIIII1Il1l1fiIIFII IYI1II1IIIITY1III 40 50 50 7O 39 1” 119 120 139 149 159 169 we 57 n-UNDECANE " cunu MW156 71 .4 .1 35 98 111TIlll1llil‘1111l11llllilIUITTIIII 1lrfi II1IIIIIIITIIIITIIIII 4. L 6. 7. 8. 1“ 11. 12. 13. 14. 150 15. 244 100 RELATIVE INTENSITY, % 8 l 7O .L-Il 83 1 - DECANOL cmuno muse X2 97 112 1 0 III]; III‘II IIIIIII IIIITAII IIII IlIII TIfiL—TlrIIIlLIIIIlIrrI 40 50 60 N 80 9. 1“ 110 12. 130 140 130 160 m/e 100 55 I-UNoECENAL ‘ c,,I-I,°o muss 33 _ x In «7: ~ [ z I E E 50‘ 32 III a .. Ii 98 III - IZI ‘1 III 0 _, l 1]. . 1 IL. I _ I I I I rI I 40 5. 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