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FINES wit] be charged if book is returned after the date stamped below. ”0 or am; n; R OM USE O [Y THE UTILIZATION OF FRACTIONATED BEEF TALLON IN FOOD SYSTEMS By Susan Beth DiIIery A THESIS Submitted to Michigan State University in partia] fquiIIment of the requirements for the degree of Master of Science Department of Food Science and Human Nutrition I982 /3’7~/0(ax ABSTRACT THE UTILIZATION OF FRACTIONATED BEEF TALLOH IN FOOD SYSTEMS By Susan Beth DiTTery AnimaT fats have traditionaTTy been used in shortening preparations. Now, with increasing cost of vegetabTe oiTs, the functionaTity and utiTization of taTTow for use in other products is being investigated. The fractionaT crystaiiization process has shown promise as a means of increasing the utiTization of taTTow. Doughnuts and batter coated chicken wings were fried in originaT taTTow, two oTein fractions obtained by fractionation and a commerciaT soybean oiT. AnaTysis of the physicaT, chemi- caT and sensory characteristics of the products and oiT reveaTed that the originaT taTTow and both taTTow frac- tions compared favorabTy with the controT. FTavor was found to be significantTy higher for aTT products when compared to the controT. White Tayer cakes were prepared utiTizing originaT taTIow, a soTid and an oTein fraction, and a commerciaT shortening and an emuTsifier. AnaIysis of the physicaT and sensory characteristics of the products revealed that the cakes prepared with originaT taTTow and both taITow fractions compared favorabiy with the controT cake. ACKNOWLEDGEMENTS I would like to thank Dr. J. Ian Gray and Dr. Mary E. Zabik for their continuedsupport and guidance throughout my graduate program and especially in the preparation of this manuscript. I would also like to extend appreciation to Dr. Jerry Cash and Dr. Bruce Harte for their assistance and for serving as guidance committee members. Susan Cuppett's help and instruction in the use of the GLC was also appreciated. - This work was made possible by a grant from the Fats and Protein Research Foundation, Chicago, Illinois. I would like to thank my mom for her never ending encouragement throughout my entire education. And to Scott for his help in the statistical analysis, but most importantly to make me see the rainbow amidst the clouds. 11' TABLE OF CONTENTS LIST OF TABLES. LIST OF FIGURES INTRODUCTION. REVIEW OF LITERATURE. Tallow. . . . . . . . . . . . Current Trends in Tallow Production Fractionation of Tallow . . Functionality of Tallow. in Food Systems Use of Tallow Fractions Deep Fat Frying Changes in Frying Fat Oxidation Polymerization. Hydrolysis. . . Health Effects of Heated Oil. Frying Technology . . Type of Fat Used for. Frying Care of Fat and Equipment Fat Absorption. Substrate Effect. Antioxidants. Fats as Shortenings Dispersion. . Shortening Power. Aeration. MATERIALS AND METHODS Deep Fat Frying of Doughnuts. Materials . . . Fractionation of Tallow Preparation of Doughnuts. Deep Fat Frying Analysis of Oil Color Viscosity . . Fatty Acid Analysis Melting Point . iii Page vi vii U) N._a_a_J—.J._I_J_a_.a #LDKDV-D-b-P-QJOKDQQOO WNNNNN OGDU'I-P—‘d 00000.) N._1_J to U) Abbbhwwwww “00000101000300 Analysis of Doughnuts. Color. . . . Texture. Moisture . . Fat Absorption Sensory Evaluation Deep Fat Frying of Chicken Materials. . . . Fractionation of Tallow. . Preparation of Chicken and Batter. Deep Fat Frying. Analysis of Oil. Color. Viscosity. . Analysis of Chicken .Wings. Color. . . . . Moisture . Fat Absorption Sensory Evaluation White Layer Cakes. Materials. . . Fractionation of Tallow. Formulation and Preparation of Cake: Analysis of Batter Specific Gravity Viscosity. . Analysis of Cake Volume . . Layer Cake Measuring Template. Tenderness and Compressibility Moisture . . . . . Texture. Sensory Evaluation RESULTS AND DISCUSSION Doughnut Deep Fat Frying Analysis of Doughnuts. Analysis of Oil. . Sensory Evaluation . Chicken Deep-Fat Frying. Analysis of Chicken. Analysis of Oil. Sensory Evaluation White Layer Cakes. . . Analysis of Batter Analysis of Cake Sensory Evaluation Tallow Variability iv SUMMARY AND CONCLUSIONS. PROPOSALS FOR FURTHER RESEARCH APPENDICES LIST OF REFERENCES Page 92 94 95 ms Table l0 ll l2 LIST OF TABLES Doughnut formulation. Stepwise preparation of dough for doughnuts Rotation of fryers in deep fat frying White layer cake formulation, AACC Method lO-90 with modification . . ... . . . . . . . . Physical characteristics of doughnuts deep fat fried in commercial oil, original tallow, and two beef tallow fractions . Physical characteristics of commercial frying oil, original tallow, and two beef tallow fractions utilized to fry doughnuts Fatty acid composition of original tallow, two beef tallow fractions and commercial frying oil initially and after eight fryings of doughnuts. Sensory scores of doughnuts deep fat fried in commercial frying oil, original tallow, and two beef tallow fractions . Melting point ranges of original tallow, 200 and 30 C olein tallow fractions and a commer- cial frying oil Physical characteristics of chicken wings deep fat fried in commercial frying oil, original tallow, and two beef tallow fractions Sensory scores of chicken wings fried in commercial frying oil, original tallow, and two beef tallow fractions Physical characteristics of AACC white layer cakes prepared with commercial shortening, original tallow, and two beef tallow frac- tions . vi Page 36 37 39 49 57 6l 64 66 68 72 76 8O Table Page 13 Sensory scores of AACC white layer cakes pre- pared with commercial shortening, original _ tallow, and two beef tallow fractions. . .,. . 86 T4 Fatty acid composition of original beef tallow from different sources and different seasons . 91 vii LIST OF FIGURES Figure I l0 II I2 I3 I4 U.S. per capita consumption of total food fats, vegetable oils and animal fats 1960-1977 (USDA, l977). . . . . . . . . . . . . . . . . . Edible tallow production and domestic usage I970-l98l. Inedible and edible tallow prices l979-l98l. An aqueous fractional crystallization scheme of beef tallow (Bussey gt 31., l98l). The stages of oxidation of a fat (Perkins, (I967) Polymerization of triglycerides (ethyl lino- leate) (Perkins, l967) . Hydrolysis of triglycerides. Phenolic "stable resonance hybrid” (Sherwin, 1972 . Some common synthetic antioxidants in use. Preparation of baked cakes for analysis. Diagram of Layer Cake Measuring Template (AACC Method l0-9l). . . . . . . . . . Flavor scores of doughnuts deep fat fried in original tallow, 200 and 30°C beef tallow fractions and a commercial soybean oil (control) plotted against fry. Flavor scores of chicken deep fat fried in original tallow, 20° and 30°C beef tallow fractions and a commercial soybean oil (control) plotted against fry. Scanning electron micrographs of white layer cakes prepared with various Shortenings. viii Page II I5 I8 I8 20 29 SI 52 70 78 83 INTRODUCTION Animal fats, tallow and lard, have traditionally been used in shortening preparations. More recently, hydro- genated vegetable oils have claimed a greater share of this market. The steadily increasing cost of vegetable oils and imported fats and oils such as cocoa butter, palm oil, coconut oil and palm kernal oil prompts the investi- gation of using tallow or fractionated tallow as potential replacements for these more expensive fats. The fractionation of tallow produces products with a wider range of use. Three definite uses for fnactionated beef tallow have been found, the olein fraction as salad/cooking oils, the solids for shortening applications and margarine formulations and the semisolid fraction as a cocoa butter substitute and/or extender (Luddy E: 31., 1973). Both solvent fractionated and aqueous (detergent) fractionated beef tallow have been found to be acceptable (Taylor _t‘al., l976). The aqueous fractional crystalli- zation is preferred due to the high cost of recovering the solvent in the solvent fractibnation method and the need for flame proof and explosion proof equipment. Used oils produce poorer quality foods on frying, the poor quality being partly due to the higher fat con— tent, off flavors, irregular browning, and poor.appearance (Artman, l969). Degradation of frying oils is measured by darkening of color of the oil, increased viscosity and the formation of oxidation products. A variety of factors can influence the degradation of an oil including type of fat used for frying, care of the frying fat, kettle design, substrate being fried and the use of antioxidants. The purpose of this investigation was to compare the functionality and utilization of original beef tallow, various fractions obtained by aqueous fractionation of tallow and a commercial control fat in food systems. Phases 1 and 2 of this investigation utilized the 20°C and 30°C olein fractions, original tallow, and a commercial soybean oil in the frying of doughnuts and batter coated chicken wings, respectively. Phase 3 compared the 250C solid fraction, 35°C olein fraction, original tallow and a commercial shortening in the preparation of white layer cakes. LITERATURE REVIEW Tallow Current Trends in Tallow Production The U.S. consumption of total food fats has increased steadily since 1950, with a particular increase in the vegetable oils and a decrease in animal fats (Figure 1) (Taylor _3 _l., I976; FOS, July l980). Both visible and invisible forms of fat have increased in the diet. Salad and cooking oils have led the increase in visible fat con- sumption, while increased meat consumption has raised the total amount of invisible fat consumption. The increase in the use of cooking oils reflects increased direct use of edible oils by the consumer, along with growing use of vegetable oils in commercial frying, roasting, and produc- tion of prepared foods. An important development in the use of cooking oils has been in the rapid growth of the fast food restaurants in the past decade (Kromer, 1980). Animal fats, tallow and lard, have traditionally been used in shortening preparations. Now, the use of hydro- genated all vegetable Shortenings is causing a shift away from these animal fats (Kromer, l980). The steadily increasing cost of these vegetable oils and imported fats 6° TOTAL FOOD FATS 50 (D 40 D Z VEGETABLE OILS :3 C) ‘L so 20 ANIMAL FATS 1962 ’64 ’66 ’68 '70 '72 '74 ’76 YEAR S. per capita consumption of total food fats, egetable oils and animal fats, l960-l977 S Figure l. U. v (U DA, l977). and oils such as cocoa butter, palm oil, coconut oil and palm kernel oil prompts the investigation of using tallow or fractionated tallow as replacements for these more expensive fats. The use of tallow has been primarily limited to inedible sources such as lubricants, soaps, feeds and fatty acid production (Taylor gt _l., l976). Edible tallow has been primarily used as commercial and institutional shortening products (FOS, Oct. l98l). If a market could be found for tallow and tallow products, much of what is classified as inedible could be edible tallow which claims a higher price (Luddy et al., I973). - Over the past decade a tremendous increase has taken place in edible tallow production while only marginal gains were made in total tallow production (Figure 2). Total tallow production has remained relatively stable at 7.0 billion pounds per year since l976 (Anon., 1978; F05, Oct. l98l). Luddy et al. (l973) postulated that inCreased beef production could increase the total tallow production to 7.0 billion pounds per year by l980. Beef production has not increased but decreased. Even though fewer cattle were slaughtered, the carcass weight was heavier, thus the goal of 7.0 billion pounds per year was attained (F05, I98l). During this same time, the production of edible tallow increased over 200% (Figure 3). This increase can be felt both in domestic use and exports, with a greater 1200 800 MILLION POUNDS 400 1 970 Figure 2. Edible tallow production and domestic usage l970-l98l. 1 980 7 .30 .25 5 EDIBLE $/Ib .20 . ' J .15 0 — 1979 1980 i981 YEAR Inedible and edible tallow prices I979—198l, Figure 3. percentage of the production staying at home. A l0% in- crease in the domestic use of edible tallow was seen from 1979/80 to l980/8l (FOS, Oct. l98l). s As indicated in Figure 3, prices of both edible and inedible tallow have fluctuated over the past three years. The decrease in price, and therefore demand, in early I980 can be attributed to record world supplies of competitive fats and oils and suspension of export shipments to the USSR (FOS, Feb. 1980). Economic recession has also suppressed tallow prices. Tallow has been used extensively in the manufacture of durable goods by the housing and auto industries which have been severely effected by economic recession (FOS, July 1980). A brighter future for tallow will be seen due to an increase in petrochemical food stocks which may increase the demand for tallow and send prices up (FOS, Oct. 1979; Feb. 1980). The large increase in production of edible tallow can be attributed, in part, to changes in the meat packing industry. Originally, carcasses were cut at the retail location into "retail-cuts" with fat trimmings going to inedible sources. Now, with centralized packing, under Federal inspection, the same fat trimmings are classified as edible tallow (FOS, Oct. l98l). Thus, the increased production needed for increased marketability can be achieved. Fractionation of Tallow Early fractionation of beef tallow was used primarily to yield pure glyceride fractions by solvent (acetone) crystallization (Brown, 1941). Solvent fractionation was also used to determine the glyceride composition of various fractions in response to temperatures (Riemenschneider _t‘_l., 1946). Several disadvantages are found in solvent fractionation; the cost of recovering the solvents is high and the equipment must be flame proof and explosion proof. Dry fractionation has also been attempted but at low tem— peratures or when small crystals are formed, filtration is virtually impOssible. Aqueous fractionation of beef tallow has the advantages of the solvent method with none of the disadvantages. A surface active agent, sodium dodecyl sulfate (SDS), and water containing an inorganic saltL(Na2504) with a par- tially Crystallized oil determines a temperature dependent fraction. Rek (T977) developed this procedure and it has been used in the fractionation of palm oil (Haraldson, 1974). Bussy and co—workers (l98l) perfected this proce- dure for use with beef tallow. The method of choice utilized the incorporation of $05 as a powder into the softened tallow at 40°C. The SDS tallow mixture was allowed to crystallize for 18 hours, than an aqueous solution of sodium sulfate (Na2504) was added and dispersed for one hour. Centrifugation followed with the ensuing IO separation of the olein and solid fractions. A decrease in temperature with no additional detergent, along with centrifugation, produced further fractions (Figure 4). A commercial procedure has been developed for large scale continuous fractional crystallization. In 1974, Haraldson delivered a paper at the Palm Oil Symposium in which he described this procedure, developed by the Alfa- Laval Company. The lipofrac procedure was developed about 1964 and has been used extensively for the aqueous frac- tionation of beef tallow in Australia. This process has also found success in fractionating palm oil. In 1974, 21 of the 25 plants operating were used for the fractional crystallization of beef tallow. Functionality of Tallow in Food Systems The functionality of beef tallow in a variety of food systems has been investigated. Early work by Morris gt_al. (1956) looked at the use of original tallow, rearranged tallow, hydrogenated tallow, and tallow-vegetable blends for shortening applications. These tallow blends compared reasonably well with standard all vegetable Shortenings and with slight hydrogenation and incorporation of antioxidants, flavor reversion was not significant. fNON? recent use Of beef tallow in shortening applications was performed by Bundy and coworkers (1981). In this investigation, solid and olein tallow fractions were used with and without ll Tallow + 0.636 503 (40°C) €18 hr. +0.015%°Na§so4 5 1 hr. centrifugation solid. .olein (30°C) 518hn~ cantrifugation solid .olein (20°C) §18hn caOntrifugation solid. Oolein Figure 4. An aqueous fractional crystallization scheme of beef ta110w (Bussey et al., 1981). emulsifier in the preparation of white layer cakes. It was found that optimum products could be prepared using solid (250C) tallow fraction with an emulsifier present. Hoerr (1960) found that tallow forms a very stable 8‘ crystal even after agalnduring normal storage. With storage under unusual conditions the 8' form polymorph did not form. M0"- crieff (1970) confirmed that for a shortening to perform satisfactorily it must be in the 8-stable polymorphic form. Holsinger et al. (1978) found solvent fractionated tallow to be acceptable as the fat component in a whey-soy nutritious beverage mix. In this experiment, the whey—soy mix, both fortified and unfortified, were stored at 370C. After storage for 6 months, no significant differences in flavor were found between the tallow samples and the control soybean oil samples. In addition, beef tallow oils were less susceptible to oxidative changes than soybean oils as determined by peroxide values. Thus, beef tallow shows promise in food systems when enhanced oxidative stability is desired. Luddy gt _l. (1973) and Taylor _3 _l. (1976) have reported on the use of a semi—solid tallow fraction as a7 cocoa butter extender and/or substitute. Luddy _g _l. (1973) investigated the acetone crystallization procedure. This procedure yielded five fractions; two solid fractions useful in shortening and margarine formulations, two liquid fractions having possible functions as salad and cooking oils, and a semi solid fraction (no. 4) with similarities to cocoa butter. The semi-solid "cocoa butter” fraction corresponds in glyceride composition and melting point curves to cocoa butter. By blending increments of a solid fraction (no. 3) with the semi solid fraction (no. 4) the melting point range can be raised thus increasing the applications of tallow by use as a confectionary coating. DeFouw _t _l. (1981) investigated the use of detergent (aqueous) fractionated beef taIIow oils and tallow oils in combination with soybean and corn oils as a deep—fat frying medium for french fries. Results of this investigation led to the use of tallow oils in deep—fat frying operations due to the physical stability of the oils and panelists accep- tance of the fried product. Use of Tallow Fractions Three definite uses for fractionated beef tallow have been found, the olein fraction as salad/cooking oils, the solids for shortening applications and margarine formula- tions and the semi—solid fraction as a cocoa butter extender and/or substitute. Both solvent fractionated and aqueous (detergent) fractionated beef tallow have been found to be acceptable. Deep Fat Frying Changes in Frying Fats During normal commercial deep-fat frying, the oil is subjected to repeated elevated temperatures usually in the presence of oxygen. These conditions can cause chemical degradation of the oil, producing a product of decreased quality. Chemical degradation can be hydrolysis, oxidation, and thermally induced polymerization. Oxidation of the oils is the chief concern in commercial deep fat frying, although with increased abuse,thermal polymerization could also possibly occur (Perkins, 1960): Oxidation. Oxidative rancidity can take the form of autoxidation or thermal oxidation. Autoxidation has been defined as the oxidation of a fat or an oil at temperatures up to 100°C, while thermal oxidation is the oxidation at approximately 200°C in the presence of air or with aeration (Perkins, 1960). In more general terms, thermal oxidation is related to a condition seen in thermally abused fata and oils with autoxidation as the condition referred to in the normal process of storage and deep fat frying. Oxidized fats are those commonly referred to as rancid with a characteristic flavor and odor. In most societies, this flavor and odor change is thought of as undesirable and the related food spoiled. In some parts of the world where refrigeration is not common place, a product may be I5 .=0 5 zm0>xo « ooogoooo ommmowm< zm0>x0 zo_btmoom_>lv.. o. o o. .. 20.253: .. .I $9.85.. . 0 0 0 O 0 .LC 9 9 .9 O. 00 o . O O O CO 0 0 0 0 o o o o 00 O . 0 O O O. o o 0 o o o o o O .0. O O o .. . . ... O r . . o o o O O 0 o . zoEmOazoomo 20.2.25". aoEma zo_._.._on_ wexomma Nassau...— 20:932. 16 considered suspect if it does not have a rancid flavor (Bennion, 1972). Oxidation occurs from the uptake of oxygen by unsaturated fatty acid components. Oxidation of food fats proceeds in a logarithmic scale due to the auto- catalytic nature of the reaction. Three phase of oxidation include initiation, propagation and termination (Bennion, 1972; Dugan, 1976). The initiation phase involves the formation of free radicals. In this stage, activation of an organic substance, usually at a double bond, causes the release of hydrogen and the resulting free radical: Initiation , activation , RH (organic substance) 9+ R- (free rad1cal) + H~ Pr0pagation occurs when oxygen is added to form a diradical: Propagation R‘ + 02 aRO' R02. + RH —+ R' + ROOH When two radicals interact termination occurs: Termination R' + R‘ —+ RR ROO‘ + ROO‘——+ ROOR + 02 R0' + R’ —+-ROR R00; + R' + ROOR 2RO' + 2R00‘ + 2ROOR + 02' The hydroperoxides and peroxides formed from this set of reactions are odorless and tasteless and therefore would not impart the characteristic rancid taste and odor. Aldehydes, ketones and esters formed from scission, dismutation and reactions of the peroxides and hydro— peroxides are the compounds which produce the characteris- tic rancid flavor and odor (Dugan, 1976). Free radicals are also released during these reactions which can thus promote further oxidation. The oxidation product is depen— dent upon the original fatty acid from which it was formed, thus the types of oxidation products can lend a clue to the fatty acid from which it was formed. Pentanal and hexanal contents are commonly used to test for oxidation of oils by gas-liquid chromatograpmic techniques (Warner, 1978) Polymerization. Polymerization of oils can Occur with the reSulting increase in viscosity. Thermal polymers form via Diels-Alder reactions between unsaturated fatty acyl groups after conjugation has taken place (Perkins, 1967) (Figure 6). These polymerization reactions may occur between two triglycerides by intermoleCular dimerization or by reaction between unsaturated fatty acyl groups on the same triglyceride molecule, referred to as intramole- cular dimerization (Ryan, 1982). Conditions leading to I8 [CH3(CH2)4:I CH =CH 011ch -.- 01101-12 [(CH2)6 00002 H5] X A heat Y I 4/ . .1. x- CH =CH =CHCHZCH2-Y X- CH2CH= CHCH=CHCH2Y CH= CH Dimer CH: CH X-CH :CHCHZ CHzY X-CHzéH :CHCHzY X- CH- CHCH2CH= CHCH2Y X-CH- -CHCH2CH= CHCH 2V Trimor _ CH ’CHCH2CH2Y XCHzctl . lCHCHzY \CH - CHCHz’CH -C\HCH2Y X-CH-CHCHZ’CH-CJ'ICHzY CH CHCHzCHzY XCH2CH CHCH2Y. Figure 6. Polymerization of triglycerides (ethyl linoleate) (Perkins, 1967). I9 polymerization of the lipids are heat stress, oxidation, and the presence of radical or polar catalysts (Dugan, 1976). Polymerization products are thought to be respon- sible for the adverse health effects attributed to abused fats and oils (Perkins, 1960). Hydrolygis. Hydrolysis (Figure 7) may occur in the fats releasing volatile short chain fatty acids, resulting in disagreeable flavors and odors. Although long chain acids are also produced by hydrolysis, these do not usually contribute to off flavors unless oxidation occurs (Bennion, 1972). Carlen gt gt. (1954), Baueverlen gt _t. (1968), and Roth and Rock (1972) found hydrolysis to be of secondary importance to oxidation. Health Effects of Heated Oils. Much has been specu- lated about the oxidation and polymerization products of oil and human health. Perkins (1960) found that animals -fed oxidizEd oils developed vitamin deficiencies. Alexander (1978) reported the effects of slight depression in growth all the way to very poor growth, diminished feed efficiency, increased liver size, fatty necrosis of the liver and various other organ lesions. 'However, the conditions used on the oil to promote these effects are far more severe than those used in the practical cooking or processing of foods (Rice _t _l,, 1960; Poling _t gl., 1960; Keane, 1959 ; Perkins and VanAkkeren, 1965; Melnick t al., 1957). For a complete review of the health effects —.——.—-‘ 20 1 a H-C-OC-R 9 . '1 ‘3 n-co-c-HR +3H20—-) H-c-ou + a RC-OH H-C-OC-R HO-C-H 1 H H-C-OH Figure 7. Hydrolysis of triglycerides. ‘3” S" i? R I". m0 —-> .. + 0:04; I . H. phenol stable resonance hybrid Figure 8. Phenolic ”stable resonance hybrid" (Sherwin, I972. 21 of heated oil see Ryan (1982). Frying_Technology type of Fat Used for Frying. The type of fat used for frying can affect.the rate and degree of oxidation. Vegetable oils are found to be prone to oxidative changes during frying and become rancid rapidly at ordinary frying temperatures due to the high amount of unsaturated fatty acids. Hydrogenation of vegetable oils makes them more suitable for deep fat frying purposes. Animal fats, with lesser amounts of unsaturated fatty acids are highly resistant to oxidative changes, especially when hydro- genated. Tallow has a superior degree of resistance to oxidation, better than that of hydrogenated vegetable oils or lard (Baeuerlen__tl_l., 1968). Degradation as measured by darkening of color was not noticeably affected by source of fat, that is, animal or vegetable (Bates, 1952; Lowe gt_gl,, 1958). Thompson gthl, (1967) indicated that the- degree of deterioration was independent of their degree of‘ unsaturation but rather dependent upon how they were used. Care of Fat and Equipment. Perkins and VanAkkeren (1965) and Ryan (1982) found that intermittently heated oils exhibited a greater degree of degenerative changes, as evidenced by increased viscosity, over continuously heated oils. This, in part, can be explained by the greater degree of oxygen available in the heating and 22 cooling period when steam rising off the 011 does not protect it. It is possible that intermittent heating, cooling and heating cycles would encourage the pestruction of the oil through an increased buildup of peroxides and carbonyl compounds which may be destroyed by subsequent heating (Perkins and VanAkkeren, 1965). Although Baeuerlen and coworkers (1968) report that turning off the heat when not required will improve turnover of fat, which is an indication of a high quality product being developed. Perkins and VanAkkeren (1965) found that a high overall turnover rate of used oil may not increase the useful life of a fat when the daily turnover of fat is small. Fat turnover increases the length of time a fat can be used as well as filtering and refrigeration of the fats (Rust and Harrison, 1960). Filtering of the oil and washing of the fryers improve the stability of the oils by reducing contaminants. Burnt food particles suspended in the frying medium tend to impart a bitter taste as well as an objectional speckled appearance to the fried product. The more burnt particles present, the more pronounced will be the bitter flavor (Baeuerlen gt _t., 1968). Gums formed on the surface and sides of the fryer which are removed during filtering and cleaning will also improve the life of a fat (Baeuerlen t 1., 1968). Improper heating elements can also accel- ~ erate the degradation of fat as well as intense heat such 23 as that over a flame (Carlin gt gt., 1954)., The uniform distribution of heat was emphasized by Strock _t gt. (1967) who found that a 10% increase in frying load could be attained with homogenous temperatures in the frying kettle. - Proper kettle design can help minimize deterioration of the frying fat. Robertson (1967) cited two principles which should be followed for kettle design. The first principlevms that the amount of fat held in a system should be the minimum amount necessary to fry the product. The second principle stated that maximum production capa- city should be maintained or that frying should be done for one long interval rather than several shorter ones. The composition of the kettle, valves and lines can have an effect on the stability of the oil. Copper, along with brass, must be avoided due to the pro-oxidative effect of the c0pper. Robertson (1967) tested various types of metals and found aluminum, nickel and stainless steel to be the least damaging in that order. However, if detergent is needed to wash the kettle, aluminum becomes impractical and the cost of nickel is prohibitive. Aeration of the fat should be avoided as with in— creased aeration there is increased exposure of oxygen to the fat (Carlin _t _t., 1954). Aeration can be reduced by preventing ”pouring“ of hot fats and circulation through heat exchangers and filters under atmospheric conditions 24 (Carlin _t _t., 1954). Placing a floating cover on the hot oil when not in use can also reduce oxidation. In addition to the previOusly mentioned factors, the length of time the fat is exposed to heat and temperature, mixed fatty acid composition and position of the fatty acid in the triglyceride, amount of fat heated, unit of surface area, and processing conditions used to refine, decolorize and deodorize the fat can contribute to the stability of a frying fat (Kilgore and Luker, 1964). Fat Absorption. The major factors influencing the amount of fat which will be absorbed during frying are: 1) cooking time, 2) the cooking temperature, 3) the total surface area of the food, 4) the composition and nature of the food, and 5) the variation in smoke point temperature of the fat used (Bennion, 1972). Time and temperature of cooking are related in that at a lower temperature more time is required to fully cook the product to the desired degree of browning. Lowe gt _1. (1940) found that doughnuts cooked for 3 minutes at 170, 185, and 2000C exhibited no significant differences in fat absorption, althOugh the color of the doughnuts was dif- ferent. Lowe and co—workers (1940) also found that re- rolling and increased handling of the dough increases the fat absorption of the doughnuts by increasing the surface area. 25 Substrate Effect The nature of the product or substrate, can influence the degradation of the oil. This effect can be manifest in three ways: 1) by the release of antioxidants or pro- oxidants from the substrate into the oil, thus protecting the oil or catalyzing the free radical formation; 2) vari- ous functional groups could have a catalytic effect on secondary reactions or also on the free radical formation in the frying oil; and 3) the substrate by adsorption or chemi—adsorption may remove lipid oxidation products from the oil (Pokorny, 1980). It has been long known that contaminant metals in the frying oil can catalyze free radical formation. Now, it is believed that hematin compounds present in meat (chicken) can leach from the product to increase the degradation of the oil (Kilgore and Luker, 1964). It was also found that the catalytic activity of hematin compounds in the chicken was offset by the deterrent effect of fat, amino acids or some unidentified protective agent in the meat (Kilgore and Luker, 1964). The protective effect of proteins was also studied by Pokorny (1980). It was found that the antioxidant effect of the protein in fried sub- strates (cod fish fillets) may be due to the effect of amino acid residues but phenolic and other compounds could contribute to this effect. Proteins are also found to bind oxidized fatty acids. These insoluble complexes are 26 only partially digested, and with difficulty, which might, contribute to the impaired digestibility of fried foods (Pokorny, 1980). Proteins, namely casein, have.been found to bind c0pper, thus removing it from catalytic activity in the frying 011 (Pokorny, 1980). Much work has been done to simulate restaurant frying conditions using moistened cotton balls (Krishnamurthy 1., 1965; Chang gt 1., 1978; Reddy t 1., 1968). It gt was found that the continuously heated oil was darker in color and had a higher viscosity than the oil which had been used to fry the cotton balls (Krishnamurthy gt gt., 1965). Chang and co-workers (1978) reported that the continuously heated oil (hydrogenated cottonseed oil) had a higher peroxide value. Fats present in the product can migrate from the pro- duct and by dilution affect the oil. Kilgore and Luker (1964) found that no decrease in linoleic acid occurred in oils in which chicken was fried. It was thought that the degradation of linoleic acid probably occurred, but the slight dilution with chicken fat, which is approximately 20% linoleic, could have compensated for the loss. Water as a component of the fried product can exert an effect on the stability of the oil. Jacobson (1967) reported that a 6% addition of water decreased the overall performance of the fat, and that a 24% addition improved the performance. Water present causes hydrolysis of the 27 frying oil, especially if catalyzed by acidic components of the fried food (Pokorny, l980). Bennion and Hanning (1956) found a greater degree of decomposition in the oils which were used to fry doughnuts in comparison to potatoes. They went on to evaluate the specific batter ingredients and found milk, eggs and baking powder to be responsible for the resulting change. Bennion and Hanning (1956) explain the results by increased poro— sity of the doughnuts with eggs and baking powder. Pokorny (1980) believes the diffusion of phospholipids with the use of egg batters increases the free fatty acid content of the oil and thus decreases sensory appeal. Darkening of the oil when the egg was included in the batter was observed. This could be due to decomposition of the diffused phospholipids in the oil (Bennion, 1967). Natural antioxidants are constituents of the substrate which provide a protective effect on the oil. Natural antioxidants are found in a variety of products: carrots, which are used in some frying production plants to delay the addition of fresh fat, offer a protective effect to the oil. It is the carotenoid pigments in the carrots which protects fat against oxidation under specific pro- cessing conditions (Pokorny, 1980). Potatoes contain natural inhibitors, the antioxidant effect located in the tuber juice (Pokorny, l980). Defatted oat flakes have been found to provide a 28% protective effect to the oil in which 28 they were fried (Pokorny, l980). Herbs and spices may have a beneficial effect by diffusion of essential oils from these products (Pokorny, 1980). One of the most common naturally occurring antioxidants is tocopherol which is found in many vegetable oils (Dugan, l976). Antioxidants Synthetic antioxidants are often added to increase the length of time the oil can be used and to increase the shelf life of the product. Antioxidants may be divided into two groups - primary antioxidants and synergists. Synergists act to enhance or prolong the action of the primary antioxidant and are usually acidic in nature (Bennion, 1972). The primary antioxidants act directly to interrupt the free radical chain mechanism in autoxi- dative processes. It is important that the free radical (A') formed not have the ability of initiating or propa- gating the oxidation reaction. Phenolic compounds form a "stable resonance hybrid" which makes it unable to function as a competitor with the substrate for oxygen (Figure 8) (Sherwin, I972) by the mechanism: R' + AH RH + A' R0. + AH ROH + A: R0' + A' ROA etc. ROO' + AH ROOH + A- 29 BHA Butylated Hydroxyanisole pa Propyl Gallate OH OH I CH3 I OH “C "' CH 3 CH3 ' CH3 -(|: -CH3 HO“ - OH I I CH OCH3 OCH3 3 ' 2 2 CH Approx. 95% < 5% (ii-0 - l I 3 O H H BHT B‘utylated Hydroxytoluene TBHO Tertiarybutylhydroquinone OH OH H36 1 CH3 I cm I I H3c- C- -C-CH3 ~C-CH3 I l I H3C CH3 CH3 l I CH3 ‘OH Figure 9. Some common synthetic antioxidants in use. 30 The use of antioxidants in deep fat frying is limited, due to the removal of the antioxidant from the oil. Magoffin and Bentz (1949) list three processes by which this can occur: the first by steam distillation; the second by adsorption in the product; and the third by the normal process of consumption in performing its antioxidant role. Sair and Hall (1951) add to this list by including the destruction or oxidation of the antioxidant. These factors, along with the resulting poor carry through of the antioxidants into the food product makes the use of antioxidants in the oils used for frying of little value (Sherwin, 1972). Sair and Hall-(1951) have found the use of antioxidant salt or an antioxidant dressing oil permits the complete utilization of the antioxidant, for use in potato chips and fried nuts. Fats as Shortenings In the cake system, fat acts to increase aeration of the batter which relates to a tender product with high volume, silky grain, and uniform cells of small size. Cake tenderness is affected by the presence of fat, which enables gluten strands to slide across one another. Fat also inhibits excessive gluten formation by physically interferring with gluten strand deve10pment (Bennion, 1972). Fats can be functionally characterized by their 3I dispersion, shortening power and aeration ability. Dispersion Dispersion of a fat refers to the degree of incorpora- tion of the fat into the batter system. Without adequate dispersion the batter is likely to have low aeration properties and decreased shortening power. Dispersions of a fat, or the surface area covered by fats, is dependent upon the cohesion, adhesion, interfacial tensions and molecular attractions between water and organic liquids (Bennion, 1972). Fat containing both polar and non-polar groups (hydrocarbon chains) is dispersed in relation to the chain length of fatty acid residues with the unsaturated acids covering much greater areas per molecule than the saturated ones (Bennion, 1972). ShorteninggPower Fats contribute their shortening ability to two interrelated factors; their molecular composition and their crystalline habits (Moncrieff, 1970). The molecular composition of a fat governs the ratio of solid trigly— ceride to liquid components. This directly affects the aeration ability of the batter. Liquid Shortenings have antifoaming properties which alone, would be ineffective in the cake system (Campbell, 1972). The fatty acid pro- file of the fat also plays an important role in the shortening ability by affecting the compositional 32 differences relating to liquid and solid components. These compositional differences affect the crystalline properties of the fat (Bennion, 1972). Aeration Batter aeration is a property associated with fat in the cake system. Although air bubbles and fat particles are dispersed separately throughout the batter, gas pockets form most readily at points of cleavage along fat boundaries (Carlin, 1944). The size of the crystal is an indication of the size of the air bubble formed. The B' stable crystals are delicate crystals no larger than one micron (u) in length. The intermediate crystals range from 3-5 H and 8 crystals are course and large, averaging 25-50 p in length (Hoerr, 1960). The 8' crystals have air bubble patterns one micron or less in diameter, the intermediate crystals present a coarses pattern of air cell distribution and the 8 crystals form large bubbles (Hoerr, 1960). To achieve maximum aeration and the resulting silky grain, the fat must be uniformly dispersed throughout the batter. MATERIALS AND METHODS Deep-Fat Frying of Doughnuts Materials Fifty pound drums of edible beef tallow were obtained from Bunge Edible Oil Corporation, Kankakee, Illinois and stored at 4°C prior to use. All reagents and chemicals used in this investigation were of analytical grade. All ingredients utilized in the preparation of doughnuts were obtained from commercial sources prior to the start of frying,with fresh milk and eggs obtained daily. Superfine All Vegetable Liquid Frying Shortening (PVO International Inc.) was utilized as the control oil and stored at room temperature upon recommendation of the manufacturer. Superfine All Vegetable Liquid Frying Shortening is made from fully refined, partially hydrogenated vegetable oil (soybean oil) with TBHQ and citric acid added to preserve stability and methyl silicone added to inhibit foaming. Fractionation of Tallow Prior to the actual fractionation procedure, tallow was chipped from the fifty pound lot to obtain the desired amount for fractionation (6.5-7.5 kg) and warmed at 400C for 8-10 hours. When the tallow was a semi-solid 33 34 homogenous mixture and free from lumps, 0.6% sodium dodecyl sulfate (SDS) was added with constant stirring (Figure 4). The SDS acts as a surface active agent to better disperse the tallow components. The SDS-tallow mixture was allowed to remain at 40°C for 18 hours. When this crystallization time elapsed, the electrolyte was added with deionized water and left to disperse for one hour at 40°C. Sodium sulfate (0.15%) was the electro- lyte of choice with 600 ml water added per kg of tallow. Five hundred m1 plastic centrifuge bottles were filled with the tallow mixture and batches of six were placed in an International Equipment Company model K, size 2 centri- fuge for 15 nfln at 2700 rpm. Centrifugation resulted in separation of olein (liquid) and solid fractions. The olein fraction was further allowed to crystallize at 30°C for 18 hr without further addition of SDS. Centrifuga- tion followed with the resulting separation of olein and solid fractions. The olein fraction was again collected and allowed to crystallize at 20°C for 18 hr with further fractionation resulting after centrifugation. An effort was made to prevent fluctuations in temperature of the tallow during handling and Centrifugation time. The solid fractions were not utilized in this experiment so, therefore, they were discarded. The tallow oils were stored at 4°C prior to use. 35 Prgparation of Doughnuts The doughnut formula of Lowe gt _t. (1940) was utilized with some modification (Table l). The type and amount of fat was adjusted to provide a neutral flavored, all vegetable shortening with the same degree of shortening ability as butter. The flour content was adjusted to provide a dough that was rollable but not overly stiff. The protein content of all purpose flour has decreased since 1940 which would make this flour adjustment necessary in order to have the equivalent amount of protein in Lowe and co-workers formulation (1940). The spice content of the doughnuts was adjusted due to pretest panelists comments. The dough was prepared by the method of Lowe 93.11- (1940) as described in Table 2. The same Kitchen Aid Mixer (model K-5A) was utilized during preparation of the dough to minimize variations in dough characteristics. Slow speed was recorded at 25 rpm and medium speed at 145 rpm. The dough was rolled by hand onto a floured board between 1/4 inch cleats. Doughnut holes, 3.0 cm in diameter, were cut with a doughnut cutter and approximately 60 g of doughnut holes (count 8) were fried per batch. Deep Fat Frying Four Sears (Model 34—6425) deep-fat fryers with alumi- num interiors and a capacity of 1365 9 oil were used for 36 Table 1. Doughnut formulation (Lowe t 1., 1940). Ingredients Lowe (9) Experimental (9) Sugar, fine granulated 200 200 Fat . 25 (butter) 20 (hydrogenated shortening) Eggs, fresh 96 96 Flour, all purpose 560 600 Milk, whole fresh 244 244 Baking powder (tartrate) 21 21 Salt 4 4 Nutmeg 1/8 teaspoon 0.40 Cinnamon 1/8 teaspoon 0.80 37 Table 2. Stepwise preparation of dough for doughnuts (Lowe gt 31., 1940). Preparation steps a Time (sec) Speed Cream sugar, salt and fat Add beaten egg Add 1/2 milk and 1/2 flour (sifted with other dry ingredients) Add remaining milk and flour Scrape down, continue mixing Scrape down, continue mixing 60 Medium 180 Medium 60 Slow 20 Slow 15 Slow 10 Slow a Medium 145 rpm, slow 25 rpm. 38 the fryings. Fryers were rotated so that the same oil variable was not heated in the same fryer (Table 3). One thousand three hundred and sixty five 9 of each oil variable were preheated not longer than 20 min to 188°C. The doughnut holes were fried for a total of 180 seconds, 90 seconds on each side. A drop in temperature of 3°C occurred when the doughnuts were placed in the oil which resulted in a cooking temperature of 185°C. Difficulty was experienced in maintaining the doughnuts on the frying side at any given time due to their tendency to roll. Two batches of eight doughnut holes were fried each day for four consecutive days. i To simulate a commercial frying operation, fat was added back to the fryers (approximately 100 g), to account for fat absorption, sample removal and drip loss, before the next day's frying began. After use, the oils were strained through a fine mesh screen layered with a double thickness of cheese cloth to remove dough particles. The fryers were washed with a mild detergent, rinsed completely and dried thoroughly. The oils were then stored in the fryer at 4°C with tight covering lids until the next day's frying began. After frying the doughnuts were allowed to cool to room temperature on wire racks then prepared for sensory evaluation or frozen for further analysis. 39 ' 1 Table 3. Rotation of fryers in deepfat frying. Replication Fryer I 2 3 4 1 20 30 OT C 2 C 20 30 OT 3 0T C 20 3O 4 30 OT C 20 20 = 20 C tallow oil. 30 = 30 C tallow oil OT = original tallow C = control, superfine A11 Vegetable Liquid Frying Shor- tening. 40 Analysis of Oil £2123: Color of the heated oils was evaluated using a Hunter Color Difference Meter (model D-25) with an inverted head and white background. A standard yellow tile was used as a reference (L=78.5, La=-3.2, Lb=23.4). Oils were analyzed for color at approximately 70°C and before straining. The oil samples were evaluated on the three scales, turned 90° and a second set of measurements were taken. Results are given as average of the two values. Viscosity. A 40 9 oil sample Was rem0ved before straining at the end of each frying day. This sample was first used for viscosity, then other determinations. Viscosity was determined using a Nametre Direct Readout Viscometer model 7.006 in conjunction with an Exacal 100 controlled temperature circulating water bath at 50°C : 0.01°C. The oil sample (approximately 35 g) was placed in a glass beaker (3.5 x 7.7 cm) and tempered in a circulating water bath. Samples were allowed to equilibrate 15 min. prior to obtaining a reading. The viscosity is given as centipoise-g/cm3. Fatty Acid Analysis. Oil samples prior to the first frying and after the last frying were analyzed for their fatty acid profiles. The samples were prepared for gas liquid chromatographic analysis using the boron trifluo- ride-methanol procedure described by Morrison and Smith (1964). The fatty acid methyl esters were analyzed as 41 described by DeFouw (1981) with a 5840A Hewlett Packard gas chromatograph equipped with a flame ionization detector. A glass column, 21nx 4 mm inside diameter, packed with 15% diethylene glycol succinate (DEGS) on 80/100 Chromosorb (Supelco Inc., Bellefonte, PA) was used. The gas chromato- graph was operated isothermally at 190°C with a nitrogen flow rate of 33 ml/min. The temperature of the injector was maintained at 210°C and that of the detector at 400°C. Fatty acid percentages were calculated for °l6’ °l6:l’ c c .fatty acids using a 18850A C and C 18’ 18:1’ 18:2’ 18:3 Hewlett Packard microprocessing integrater. Melting Point. Melting points of the oils prior to use and after each consecutive day of frying were deter- mined by positioning the heated oils in a micro—capillary tube, sealing the end, freezing at —26°C and slowly heating the suspended capillary tube and thermometer in a circulating ice water bath or acetone dry ice bath deter- mined upon the melting point of the oil sample. Analysis of Doughnuts £212£~ Both of the batches of doughnut holes fried daily were analyzed for color using a Hunter color Differ- ence Meter (model D-25) with an inverted head and white background. A standard white tile (L=91.04, La=l.0, Lb: 0.9) was utilized for reference. Two readings were taken on each sample with the mean of the four values reported. 42 Texture. The doughnut holes were evaluated for tender- ness using an Allo-Kramer Shear Press equipped with a TR-3 recorder. Five doughnut holes were weighed to the nearest 0.01g1and placed in the standard shear compression cell. The 3000 lb. transducer was used with a range of 300. Readings were recorded and pounds force to shear 1.0 g was calculated using the formula: transducer x range x reading 1b force/g = sample wt (9) x 100 x 100 Moisture. The A.A.C.C. Method 44-40 Moisture-Modified Vacuum Oven Method (1961) was followed to obtain percent moisture in the doughnut holes. The thawed, hand ground samples (2-3 9) were weighed to the nearest 0.0001 g and placed in predried, preweighed aluminum moisture dishes. The samples were dried at 90°C for 12-15 hours under a vacuum of 27 inches of mercury in a Hotpack Vacuum Oven model 633. The samples were allowed to cool 30 min in a desiccator before being reweighed. Percent moisture was determined from the formula: or1g1na1 wt - dr1ed wt x 100 % m01sture = original wt Fat Absorption. Fat absorption was determined for the thawed, hand ground doughnut holes by the A.A.C.C. Method 30-25 crude fat in wheat and soyflour, feeds and cooked 43 feeds (1962). A 4-5 9 sample was accurately weighed to the nearest 0.0001 g and placed in a 3.3x8.0cm1 Soxhlet thimble plugged with glass wool and gently lowered into a 50/55 soxhlet condenser. A 250 m1 aliquot of reagent grade hexane (undistilled) was added to a 500 ml rounded bottom flask with 4-5 glass boiling beads. The apparatus was assembled and left to reflux for 6 hours on medium heat. The total volume of the filtrate was recorded and a 50 m1 aliquot (using a 50 ml volumetric pipette) was removed for analysis and placed in‘a predried, preweighed 125 ml Erlenmeyer flask. Approximately 40-45 ml of the hexane were allowed to evaporate on a steam bath before the sample was placed in a 70°C Labline (model 3615) oven under a vacuum of 30 inches of mercury for 12-15 hours. The samples were allowed to cool 30 min in a desiccator before being reweighed. Percent fat in the sample was determined from the formula: wt of extracted lipid (g) % fat : sample wt (9) X total vol of extract (ml) ‘50 m1 x 100. Fat content was expressed as percentage of total solids. Conversions were made by the formula: 44 % fat (wet basis) (100-% moisture of sample) % fat (solid basis) x 100. Sensory Evaluation. An eight member untrained panel was used to evaluate the doughnut holes. Each panelist was presented with four doughnut holes, each corresponding to a specific variable. The panelists were asked to judge each sample independently for crust color, tenderness, fat absorption and flavor on a 10 point descriptive linear line scale with 10 being optimum and 1 as poor. All evalu- ations were done in individual booths equipped with simu- lated daylight. The same eight panelists were used for the duration of the study. Degp Fat Frying of Chicken Materials Fifty pound drums of edible beef tallow were obtained from Bunge Edible Oil Corporation, Kankakee, Illinois and stored at 4°C prior to use. All reagents and chemicals used in this investigation were of analytical grade. A common lot of chicken wings was obtained frozen from a commercial supplier. The batter for the chicken wings was prepared using Drake's Crispy Fry Mix manufactured by Drake's Batter Mix Company. Ingredients of the batter mix consist of wheat flour, cornmeal, salt, whey, bob-fat, dried milk, sodium bicarbonate, ground herbs, and spices. 45 Fractionation of Tallow Beef tallow was fractionated as discussed previously for deep fat frying of doughnuts. Prgparation of Chicken and Batter The chicken wings needed for each day of frying were thawed prior to use. Batter for the chicken was prepared following the package directions, 1.1 9 water: 1 9 mix. Just prior to frying the wings were submerged in the batter to coat the pieces thoroughly. Deep Fat Frying Four Sears (Model 34-6425) deep fat fryers with alumi- num interiors and a capacity of 1365 9 oil were used for the fryings. Fryers were rotated so that the same oil variable was not heated in the same fryer (Table 3). After use, the oils were strained through a fine mesh screen layered with a double thickness of cheese cloth to remove batter particles. The fryers were washed with a mild detergent, rinsed completely and dried thoroughly. The oils were then stored in the fryers at 4°C with tight covering lids until the following trial. A 1000 9 sample of each oil variable was preheated not longer than 20 minutes to 200°C. Three wings were fried in each batch for 10 minutes. An initial drop of 10°C was experienced such that the cooking temperature remained approximately 190°C. Three batches of wings were fried 46 daily for four consecutive days. To simulate a commercial fat was added back to the fryer to maintain 1000 g for each days frying. Approximately 150 gvune added back daily to replace fat adsorption, drip loss and sample removal. After frying, the wings were allowed to cool to room temperature on wire racks, then prepared for sensory evaluation or frozen for further evaluation. Analysis of Oil Color. Color of the oils was evaluated as described previously for deep fat frying of doughnuts. Viscosity. Viscosity of the 0ils was evaluated as described previously for deep fat frying of doughnuts. Analysis of Chicken Wings tglgt. Due to the size of the chicken wing and the non-uniformity of surface flatness, color results using the Hunter Color Difference Meter could not be accurately determined. Moisture. The method described for calculating percent moisture of the doughnuts was followed for the chicken wings. The sample included only ground homogenous batter. Fat Absorption. Fat absorption by the chicken was determined from the fried batter. Batter was removed entirely from one wing and ground for 45 seconds in a Waring Blender (model 1120). The procedure followed that described for deep fat frying of doughnuts. 47 Sensory Evaluation. An eight member untrained panel was used to evaluate the chicken wings. Each panelist was presented with four chicken wings, each corresponding to a specific oil variable. The panelists were asked to judge each sample independently for crust color, tenderness, fat absorption and flavor using a 10 point descriptive scale. The chicken samples were evaluated after they had been heated for 60 seconds in an Amana Radarange Microwave Oven (model RR 9TA) on full power. White Layer Cakes Materials A four hundred pound drum of edible beef tallow was obtained from A.W. Stadler Company, Cleveland, Ohio and stored at 4°C prior to use. All reagents and chemicals used in this investigation were of analytical grade. All ingre- dients were obtained from commercial sources in common lots and stored at room temperature until use. Vanall Cake Emulsifier was obtained from Patco Products. Vanall is a hydrated (66%) blend of Sorbitan monostearate, glycerol monostearate, polysorbate 60; with propylene glycol, lactic acid and sodium pr0pionate included as preservatives. Fractionation of Tallow In this investigation, solid and olein fractions were utilized with the crystallization temperatures of 40°, 35°, 48 and 25°C. The resulting 35°C olein and 25°C solid fractions were utilized as Shortenings. The fractionation procedure followed that described for deep fat frying of doughnuts. Formulation and Prgparation of Cake Formulation and preparation of the cakes followed the A.A.C.C. Method 10-90, Baking Quality of Cake Flour. The formula is given in Table 4, along with modifications. The formula was scaled down to be applicable to a seven inch diameter cake pan. Pretesting determined the optimum water level in the formula and optimum baking time. Emulsifier was added at the 3.0% level as suggested by the manufacturer and recommended by Bundy _t _t. (1981). The amount of baking powder was determined by the Barometric pressure on the day of bake (A.A.C.C. Method 10—90 page 3 of 3). The A.A.C.C. Method 10-90 was followed for the preparation of white layer cakes. The same Kitchen Aid Mixer (model K—SA) was utilized during each preparation of the cake batters to minimize variation in batter characteris- tics. Low speed was recorded at 100 r.p.m. and medium speed at 200 r.p.m. The cakes were baked individually at 375°F in a Rotary Hearth Test Baking Oven (model MF-2-665KLP220) for 25 minutes. Four replications were performed on each variable. 49 Table 4. White layer cake formulation, AACC Method 10-90 with modification. Ingredient AACC Method 10-90 Modification 9 % g i % Cakeflour (14% 200.0 100.0 87.50 100.00 moisture basis) Sugar (Baker's 280.0 140.0 122.50 140.00 special) Shortening 100.0 50.0 43.75 50.00 Nonfat dried milk 24.0 12.0 10.50 12.00 Dried egg white 18.0 9.0 7.88 9.00 Salt 6.0 3.0 2.63 3.00 Baking powder a ‘a 4.59 5.25 Water, distilled b b 130.55 145.00 Emulsifier - - 2.63 3.00 aOptimum determined by Barometric pressure on day of bake. bOptimum inclusion determined by pretesting. 50 Analysis of Batter Specific Gravity. Specific gravity of the cake batters was determined gravimetrically at 23°C using the formula: wt of substance + cup - wt of cup wt of water + cup - wt of cup specific gravity = Viscosity. Batter viscosities were determined using a Brookfield viscometer, Model RVT, which utilizes a rotating spindle (no. 6) and variable speed (speed 10). Readings were recorded and viscosity (centipoise) was calcu- lated from the formula: centipoise (cp) = reading x factor; where the factor = 1000 for spindle 6 and speed 10. Analysis of Cakes Cakes were proportioned for analysis as shown in Figure 10. Volume. Volume of the baked product was determined by rapeseed displacement utilizing the National Loaf Volumeter with a 1000 cc capacity. Frozen cakes were cut in half with the sum of the volume of both halves of the cake recorded as the total volume. Volume index, and additional volume measurement, was determined utilizing the Layer Cake Measuring Template (A.A.C.C. Method 10-91). Layer Cake Measuring Template (A.A.C.C. Method 10-91). Volume index, symmetry index, uniformity index and shrinkage 51 \\\\\\ TENDERNESS SENSORY MOISTURE TEXTURE I SENSORY COMPRESS— lBlLITY \\ Figure 10. Preparation of baked cakes for analysis. 52 were measured on the half cakes. Figure 11 diagrams the layer cake measuring template. A B C D E ...0.°...... ......O.... (— 17,5 cm ) Figure 11. Diagram of the Layer Cake Measuring Template. From the following formulae,the index values and shrinkage can be calculated: volume index = B + C + D II N 01 I w l U symmetry index uniformity index = B - D shrinkage = 17.5 cm - (distance A through E) Tenderness and Compressibility. Tenderness (pounds force per gram to shear) and compressibility (pounds force to compress) were recorded for each variable with the use of an Allo-Kramer Shear Press equipped with a TR-3 recorder. Round (compressibility) and square (tenderness) forms were used to cut standard samples and those for tenderness 53 evaluations weighed to the nearest 0.01 g. A standard shear compression cell was used to measure tenderness. The 3000 lb. transducer was used with a range of 10. Readings were recorded and pounds force per gram to shear was calculated using the formula:' transducer x range x reading sample wt (9) x 100 x 100 lb force/g = Compressibility was determined using a round plunger (Model SC 116) which compresses the cake sample against a platform. The 100 1b. transducer was utilized with a range of 33. Readings were recorded and pounds force to compress was calculated from the formula: _ transducer x range x reading lb force — 100 x 100 Moisture. Moisture content of the baked products was determined by the procedure outlined for doughnuts. Texture. Texture of the baked product was determined by scanning electron microscopy (SEM). Randomly selected cube samples were freeze dried for 24 hours, mounted on aluminum stubs, and gold coated with a sputter coater for 9 to 12 minutes. The prepared samples were examined in a Japan Electrol Optics Limited SEM, Model JSM 35C, at an accelera- ting voltage of 15 KV and 20 X magnification. 54 Sensory Evaluation. Cakes were judged by an eight member untrained taste panel for cell uniformity, size, and thickness of walls; grain; texture, moistness, and softness; crumb color; and flavor. The A.A.C.C. Method 10—90 score card was utilized.' The conditions of the evaluation were similar to those described for doughnuts. RESULTS AND DISCUSSION This study was designed to investigate the function- ality of detergent-fractionated beef tallow and original beef tallow in food systems. The application of these tallow fractions as well as intact tallow was studied in deep fat fried foods and baked products, with both objec- tive and subjective analyses being conducted. Degp Fat Frying of Doughnuts In this phase of the investigation, original beef tallow and two beef tallow olein fractions (20 and 30°C) were evaluated as frying media for dough systems. In order to simulate a commercial Operation, fresh fat was added back to the fryer after every other fry. Doughnut Analyses Tenderness of the doughnut holes as measured on an Allo-Kramer Shear Press revealed that the control sample (Superfine All Vegetable Liquid Frying Shortening) dough- nut required more force to shear (194.6 lb/g) and was significantly (p<0.05) less tender than either the original tallow sample (169.3 lb/g) or the doughnut prepared using the 20° and 30°C fractions (181.3 lb/g and 178.5 lb/g, 55 56 respectively, Table 5). A statistically significant difference was noted among fries for this evaluation. Increased use of the oils produced doughnuts which were significantly less tender. The color, or degree of browning of the fried product is an indication of the quality of the oil. Irregular browning and decreased overall browning of the fried products is an indication of overuse of the frying oil (Artman, 1969). Color of the doughnut holes was consistent throughout the frying replications, thus degradation of the oils was not indicated. No statistically significant difference was found among doughnuts for all tallow samples and the control (Table 5). DeFouw gt gt. (1981) reported a significant difference between color of sliced fried potatoes over a period of twenty fryings utilizing °, 35°, 40° and 45°C tallow fractions. Fried potato 25 slices were darkest and most red after the first frying: however the color of the fried sliced potatoes from the sixth through the twentieth frying did not differ signifi- cantly. Rust and Harrison (1960) also found that french fried potatoes did not brown after approximately 19 frying periods. DeFouw (1981) attributed the lack of browning to the decreased ratio of potato slice weight to oil weight. Adding fresh fat back to the fryer will increase this ratio and extend the useful life of an oil (Melnick, I957b; Artman, 1969). Adding back of fat dilutes the 57 .Amo.ovav mucmgmwwwu pcou_wvcmwm o: mpmowvce smupm— mEmm an vmzo__ow memos zomono .A.0:H Focowpmcgmch o>mv newcmpeozm mcwxgd vwscwb m—nopmmm> __< mewCLoazmm .mcowpmoerame L30C co cmmom < o._nwm.o_ o._uem.e_ . e.~uem.e_ N._uom.m— p ©.ouo_.om N.ouoo.om N._new.m_ e.Fuom.m_ m m._umm._m N.muom.mm N._nmm.mm N.Nuom.om 4 LOPOQ Lopes: em.onowm.m_ _e._uooo.mF mm.oumem.nfi me.ouomm.m_ & .oezpmeos eo.mnmmm.mm. em.mummo.em em.mumoe.mm ee.muomm.mm & .COWOQLOmDm “we m.m_nnm.me_ m.m_unm._m_ m.munm.mo_ ©.m_nom.em_ m\n_ .mmmcemucmp uoom uoom zoFFmp Fwo meexge meowuuecy FoCmeLo meowuemssoo mowpmwempuoeoco < .mcoepomgw zoFFou Coma 03p ocm .3o__mu Focwmweo .Fwo mCWXLC FmAOLOEEou Cw vowew pow ammo mpzczmzoo Co mo_pmweopomsoco Fo0_mxca .m m_nme 58 degradation products, as well as producing a fresh matrix for frying (Ryan, 1982). Speckled appearance of foods fried in used oils has been reported (Beaverton _t _t., 1968). Speckling was not found for the doughnuts fried in any of the oil samples, most probably due to filtering of the oil and washing of the fryers after every second fry. The doughnuts fried in original tallow had the highest degree of fat absorption, 27.46% although no significant differences were found between samples. The control sample had the lowest fat absorption (23.23%), while the 20° and 30°C fraction doughnuts contained 24.62 and 23.85% fat, respectively. Fat absorption in fried foods is related to time and temperature of cooking as well as total surface area and composition of the food (Bennion, 1972). Time and temperature of cooking are related to fat absorption, such that at a lower temperature more time is required to fully cook the product. Thus, the product is in contact with the oil for a longer period of time. Lowe gt gt. (1940) reported that there were no significant differences in fat absorption for doughnuts cooked at three temperatures, 170°, 185° and 200°C, the cooking time being the same at all three temperatures. It is unlikely, therefore, that fat absorptin would be affected by the slight fryer temperature cycling experienced in this 59 investigation. Lowe _t _t. (1940) reported that fat absorption was influenced by dough temperature. If the dough was 24°C, the doughnuts absorbed more fat and did not expand as much before cooking whén the dough temperature was near 26°C. The longer the dough was handled and rerolled the less fat was absorbed during frying (Lowe gt gt., 1940), quite possibly by the porosity effect experienced (Bennion and Hanning, 1956). The dough for doughnuts in this investiga- tion was prepared in one batch for all frying on a given _ day. Therefore, the effect of dough temperature and handling would be negligible. 7 Used oils produce foods of poorer quality, the poorer quality being manifest as higher fat content, off flavors, irregular browning and poor appearance (Artman, 1969). In this investigation, fat absorption was not found to in- crease with increased frying which relates to an oil which was not overused. This is supported by consistent browning and acceptable appearance of the doughnuts and the lack of an increase in viscosity of the oil. The moisture contents of the samples were found to range from 17.5 to 19.0%, although no significant differen— ces were noted between samples (Table 5). It is possible that during freezer storage, a loss of moisture could have occurred which would account for the small differences in moisture contents. 6O Analyses of Oil The viscosity of the original tallow sample was not significantly different from that of the tallow fractions, while the control sample was significantly less viscous (Table 6). In general, the viscosity of oils decreases slightly with an increase in unsaturation (Swern, 1964). The lower viscosity of the commercial frying oil, 29.5 cp-g/ cc3 could be due to the more unsaturated nature of this vegetable oil. The 20°C olein tallow fraction is more unsaturated than the 30°C olein fraction which is more unsaturated than the control (Table 7). Although no significant differences in viscosity were found, the unsaturation of vegetable oils increases the potential for oxidation and polymerization of the oil, with the concom- mitant increase in viscosity (Baeuerlen _t _t., 1968). Increased viscosity of the oils also relates to a frying mediwnwith poor heat transfer properties (Artman, 1969). It is significant to note that no increase in visco- sity was found with increased fryings. This indicates that polymerization products were not formed to any significant level. This supports the work of Ryan (1982) who reported that both continuously and intermittently heated oils did not show an increase in viscosity until after 25 hours. DeFouw _t _t. (1981) in contrast, reported a significant increase in viscosity in the frying media after frying six batches of sliced potatoes. The difference 6I Amo.ovav moemcmtewv pcmowacmwm o: opmuwocw emume mEom mp voZOFFOC memos so; A.ucH Focowpmccuch o>ev mercmpcocm mcwxgd vwzcwe mFQmpmmm> __< ocwwgmazm one m meoweoue—ame Lao; :o ummmp< m.ouem.o- e.ouee.o- e._uee._- m.ouoe.m+ e N.ouem.m- N.onoee.m- e._uoe.m- m.ouem._- e m.oneo.oe . N.oueo.me m.NnoP._N e.oneo.m_ u Lo—oo ngcsx m.oneo.mm m._nem.mm e.onem.mm e.muem.mm moo\m-eo Aoemoome> uoom UooN zoFFmp _wo meexcw meowpumew Focwmwgo mfimwuLmEEou mv mcwcmpgogm mcwxgd uwzcwb mFQmpmmo> FF< 0:?wemazmm ,6 Loon o .Esewpao or new; mmfiom pa OP ”Posed mpmmp LmnEmE unmet mmcowpoOVFQOL L:OC co ummon< 6 m.OHn©.m m.OHnm.m «.0Hnm.m m.Ome.m Lo>w~w m.OHmm.m N.OH m.m ¢.OH v.w n.0H o.w Lo—oo pngo . m m m N.OHUQ@.N m.OHQm.m m.owom.m N.OHmw.© :oprLOmnm paw ¢.OHm¢.m N.0Hm~.m q.owm¢.m m.OHmo.m mmmCLmvcmu uoom UoON Zoe—mp m_wo mcwxgm mcovuomgw _mcwmweo meucmesoo (\muepmwgmpooemzu .mcowuumcm ZOFqu Come 0:» use .zorpmp Focrmeeo .Fwo mcwxcw _owocmeeoo cw covet pow ammo mpzccmzov Co mmLOOm xgomcmm .w OFDoe 67 a score of 7.9. The tallow fractions were located midway with scores of 7.3 and 7.6 for the 20°C olein fraction and 30°C olein fraction samples, respectively. These values do not correspond to the objective fat absorption results in which no significant difference in fat absorption was found. DeFouw _t _t. (1981) also reported this lack of continuity in fat absorption of fried potato slices. Original tallow fried potato slices were found to be less greasy by sensory evaluation than those fried in tallow fractions, although no significant difference existed among the objective fat absorption results for slices fried in h original tallow and those fried in tallow fractions (with the exception of the 25°C olein fraction). The original tallow has a lower melting point, being a solid at room temperature (Table 1). This could impart a different mouth feel to the doughnuts and potato slices fried in original tallow. One of the principal uses of fats in food preparation is to impart textural qualities to the food including mouth feel (Bennion, 1972). The panel members might have related this difference in mouthfeel to a decreased greasiness and scored the sample thus. Flavor was found to be equally acceptable among the doughnut holes fried in any of the tallow samples, although a significant decrease in acceptability was noted for the commercial frying oil (Table 8). The tallow samples (both fractions and original tallow) averaged 7.7, with the 68 Table 9. Meltino point rangesA of original tallow, 20°C and 30°C olein tallow fractions and a commercial frying oil. Oil Melting point, °C original tallow 41-43O 20°C fraction 21-230 30°C fraction 23-26° commercial frying oilB -9.0—4.0° Abased on three replications °Superfine All Vegetable Liquid Frying Shortening (PVO International, Inc.). 69 control doughnut achieving a score of only 5.3 on a 10.0 point scale. Figure 12 illustrates the flaVor scores plotted against fry number. Flavor deterioration was not a problem with the doughnuts in this investigation. The low flavor scores-for the control doughnut could be due to reversion of the commercial soybean oil. Soybean oil is classified as a linolenic acid vegetable oil. This class of oils, and soybean oil in particular, is susceptible to reverting in flavor to the undeodorized form of the soy- bean. The flavor and odor of the undeodorized or reverted soybean oil are described as "grassy", “beany” and ”fishy“ (Swern, 1964). These characteristic flavors and odors were reported by panelists for the doughnuts fried in the commercial soybean oil. The oil for the deep fat frying of doughnuts was purchased just prior to the start of this investigation. Deep Fat Frying of Chicken In this phase of the study, original beef tallow and two beef tallow olein fractions (200 and 30°C) were inves- tigated in the frying of a batter system. In order to simulate a commercial frying operation, fresh fat was added back to the fryers after every third fry. Chicken Analyses Fat absorption (dry basis) of the chicken wings ranged from 34.60% for the chicken fried in the 30°C fraction to 70 10 a |.l.l ....................... m 6 O‘ °°°°°°°°°°° 0 '0. ......... 0 ........ O (I) 4 H 20°C FRACTION 2 Duo 30°C FRACTION H ORIGINAL TALLOW O°°O CONTROL Figure 12. Flavor scores of doughnuts deep fat fried in original tallow, 20° and 30°C beef tallow fractions and a commercial soybean oil (control) plotted against fry. 71 40.24% for the control sample. The sample fried in original tallow and the 20°C fraction sample contained 36.93% and 38.71% fat, respectively (Table 10). These differences are nOt significant. A large standard deviation was found for the 30°C fraction sample. This also corresponds to a large standard deviation for moisture. No significant difference was noted for moisture. The average moisture content for all samples was approximately 26%. Both fat absorption and moisture contents were obtained from the breading only of the chicken wing. It is possible that the oil was absorbed into the chicken itself which would account for the large standard deviation noted. Pokorny (1981) reported the pro- tective effect exerted by protein rich foods due to the adsorption or chemiadsorption of lipid oxidation products in the fried substrate. Kilgore and Lecker (1964) inves- tigated the linoleic acid content of fried chicken and found less of a decrease in the oil used to fry chicken than in the oil used to fry potatoes. Neither of these investigations used battered food products. A lack of uniformity in thickness of batter was experienced. Variable thickness of batter could result in varying levels of fat absorption and moisture loss. The batter mix contains baking soda and milk, both of which have been shown to increase fat absorption in doughnuts by increasing the porosity of the dough (Bennion and Hanning, 1956). The shape and variability of shape of the chicken 72 Amo.ovav mocmeomtwu pcmowtecmwm o: mpmowccw mepm_ 05cm An umZOFPOC memos so; A.ucH _ccowpoccmch o>dv mcwcmucocm mcwxcd oeuvre m—nopmmm> __< mcwtcmasm one m meowpouw_qme L30» :0 women < m.ouc¢.m m.ouco.m _ o._unm.m N.ouom.o_ n m.ouom.o e.ounm.o m.ouno._ o.~nnm.m c o.on o.mp m.ouom.m_ q.ohnm.m_ m.—non.o_ 4 a LOFQU Loves: 06\m-ao N.Nnoe.mm o._uoo.mm m.ounm.mm m.FHoq.mm .xpwmoomw> Pro ee.muoem.mm. oo.mwome.gm m©.ehcmo.mm mm.¢nm_m.mm R .oespmwoe & .corpacomnm __.mnooo.¢m oo.muo_m.mm em._ummm.om o_.mncqm.oq pct :mxo_;o uoom ooom ZOFFoO m_?o mcwch meowpocct _ccwmweo _mwongEou movemecmpoocozu .mcoepomey ZOFFou moon 0:“ use zoprop _mcwmweo .Fpo < mcwxcm FowocmEEoo :_ covey pew ammo mace; cmxuwco Co muwpmwcmuowcmgo Foowmxga .o_ mFQmH 73 wings caused the batter to accumulate in some wing loca- tions. To avoid this problem, deboned chicken of uniform size and shape should be used. Improper packaging of the chicken during freezer storage, repeated freezing and thawing could also account for the variable moisture and fat contents in addition to the factors discussed for doughnuts. Anatyses of Oil The beef tallow fractions were found to have the highest viscosity followed by the original tallow and the control (Table 10). No significant difference (p<0.05) in viscosity was found between the fractions, However, the fractions were significantly more viscous than the original tallow, which in turn was significantly more viscous than the control. The control oil had the lowest viscosity of 24.4 cp-g/CC3, which was very similar to the 22.8 cp-g/CC3 found in the doughnut evaluation. The viscosity of the original tallow was also quite similar in both investiga- tions with 28.8 cp-g/cc3 in the chicken evaluation and 29.5 cp-g/cc3 in the doughnut evaluation. The significant increase found in the 20° and 30°C fractions, 35.6 and 35.4 cp-g/Cc3 respectively, could be due to the increased use of the oils in the chicken evaluation than in the frying of doughnuts. A greater frying time was needed for chicken and three fries per day were utilized in contrast 74 to two fries per day for doughnuts. The increase in viscosity of the fractions could be explained by the increased unsaturation of these oils in comparison to the original tallow. With increased unsatu- ration of an oil,'a greater potential for oxidation and polymerization exists, which results in increased viscosity Hheuerlen gt_gt,, 1968). The control oil which was more unsaturated than the tallow fractions only displayed a slight increase in viscosity in this investigation. No significant increase in viscosity was found with increased frying. Color of the commercial oil was found to be signifi- cantly darker, more red and more yellow than any of the tallow oils which were all very similar. This color pattern was similar to that found for the oil used to fry doughnuts, with the exception of the differences noted between the original tallow and the fractions for the doughnut frying. Bates (1952) and Love gt gt. (1958) reported that darkening of color of heated oils is not noticably affected by source of fat, whether it be animal or vegetable. Sensory Evaluation Sensory scores for the chicken wings displayed a similar pattern to that of the doughnuts with no signifi- cant differences noted for tenderness and crust color 75 (Table 11). All samples for both tenderness and crust color scored at least 8.0. Fat absorption was rated as lowest in the 30°C fraction sample with a score of 5.5. All other samples scored 6.4 for fat absorption. This is inconsistent with'the findings of the doughnut evaluation results. Overall, the scores were much lower for the chicken sensory fat absorption results, averaging 6.2 in contrast to those for the doughnut fat absorption averaging 7.4. The difference could be attributed to the thickness of the batter. This type of batter coating appeared to be relatively thick thus permitting a high degree of fat absorption. Panelist comments reflected a preference for chicken with a lesser amount of batter and therefore less greasy. The chicken was also heated before being sampled by the panelists which would impart a different mouthfeel upon the products. Flavor for the chicken, like that of the doughnuts, was found to be significantly less acceptable for the commercial soybean oil which received a score of 6.8. The tallow samples ranged from 8.3 to 8.4. The chicken flavor scores were higher (averaging 8.0) than the doughnut flavor scores (averaging 7.1). The chicken was also fried longer which would lead to increased fat absorption over that of the doughnuts. Several reasons can be given to explain the overall higher flavor scores for chicken: 1) the panelists chosen were basically untrained, therefore error 76 Amo.ovev monoLoCCWU oneowmwnmwm on opeowo:e Lmuum— mEem An negoP—om mceoe so; one A.ocH .PecownencoWCH o>mv onecouconm mcwad nwacen ofineummm> ~_< neweeweemm Focee opmen Lenses onmwo menowueo__aoe Leo; no nomen< m.onne.m m.onnm.m e.oene.w N.oeem.n co>e_c n.0eee.m n.0nen.m m.onen.w o._eee.m Lo_oo pmzco m.onnm.m e.onee.© n.0eee.n m.oeee.n cowueLOmne new n.one_.m e.oeen.m n.0nem.w e.oneo.m mmoccoecoo uoom uoom zoFFep meo mcwxct meowpoece Fecemwco _ewoLoEEoo oxen e.eunm.ee e.enoe.e_ A._none.om _.mnee.ee nomeoav enemoomes eo.onnoe.q ee.onoee.o No.0nnoa.o No.0neme.o eoesece oeeeooea coeeee cemFo comm eWFOm oomm zoFFep mcwcmpconm meowooeea Feeem_co m_e_ocoEEoo moepmweopoeeenu < .mcoeuoeee zo__en Coon ozo one .ZOFFeu Fecwmweo .mcwcmpeone _eeocoEEoo new; noceeoce moxeo coxen open: uu<< Co movemecopoeeeno _eoemxna .N_ aneH 81 volume and volume index: among any of the samples (Table 12). Volume of the baked products averaged approximately 775 cc. Even though statistical differences in specific gravity and viscosity of the batter existed, these differ- ences in aeration'did not effect volume of the baked products. No difference was noted for uniformity index, symmetry index and shrinkage. The term “uniformity" has been applied to measure cake symmetry and "symmetry" to indicate contour. Therefore, all cakes in this investiga- tion had neither sunken centers nOr peaked tops. Shrinkage for all cakes was less than one centimeter. Tenderness of the cakes is an indication of the shor— tening ability of the fat. The tenderness values followed a trend with the cake shortened with the 35°C olein fraction as the most tender with 0.90 lb/g force to shear, followed by the cake with 25°C solid fraction sample with 1.08 lb/g, the control cake with 1.23 lb/g, and the cake prepared with the original tallow as the least tender needing 1.40 1b/g force to shear. No significant difference was found between the control cake and the cake prepared with the 25°C solid fraction fat. Hornstein _t gt. (1943) as cited by Bennion (1972) suggests that a greater tenderizing power exists in unsaturated liquid fats which is due to a greater spreading of the liquid fat over the flour surface because of the attraction of the double bonds. The olein fraction is the most unsaturated of the shortening samples (Bussey t al., 82 1981) which could explain the increased tenderness for the olein fraction. The original tallow cake took the most force to compress 10.88 lb, but no significant differences existed in compressibility of the cakes. Moisture content of the products averaged approximately 70%, with no signifi- cant difference found among samples. Texture of the cakes, as an indication of cell size, uniformity and thickness of walls was determined using SEM (Figure 14). As can be seen, the cake prepared with hydro- genated vegetable shortening (CrisCo) has larger air cells, with the tallow cakes looking very much alike. The cake prepared with Crisco has an average cell diameter of 400 u, whereas the tallow cakes has an average cell diameter of 300 u. This difference could be attributed to dispersion of the fat in the cake system and the emulsifier present. Unsaturated fatty acids cover greater areas per molecule than saturated fatty acids, and thus their dispersion is greater (Bennion, 1972). The commercial vegetable shorten- ing contains more saturated fatty acids than the tallows (Home and Garden Bulletin No. 72; Bussey gt gt., 1981), which could account for the decreased dispersion and the resulting increase in cell diameter. The emulsifier added to the tallow cakes in this system, Vanall, contains a variety of different emulsifiers (Sorbitan monostearate, glycerol monostearate and polysorbate 60) each of which have different emulsifying characteristics in the batter system. 83 250 C solid fraction 350 C olein fraction beef tallow beef tallow original beef tallow Crisco Figure 14. Scanning electron micrographs of white layer cakes prepared with various shoternings. 84 Crisco, in contrast, contains only mono and diglycerides. This difference in type of emulsifier present in the cake system (and possibly amount) could have caused the air cell size variation. Also, the increase in volume of the control cake, though insignificant, could have lead to this effect. The polymorphic form of the fat is also important in determining the batter characteristics and final cake grain and texture. Original tallow and fresh hydrogenated vege- table oils both exhibit the 8' polymorph (Hoerr, 1960). No research to date has been reported on the crystalline habits of beef tallow fractions. It is assumed that both the 35°C olein sample and the 25°C solid fraction fat also exhibit the 8' polymorph due to the extreme stability of the 8' crystals found in original beef tallow (Hoerr, 1960). It is possible that the solid fraction is not as 8' stable due to the increased amount of solid components present. The presence of SDS might also cause crystal modification (DelVecchio, 1975). The 8' crystalline structure of a shortening is necessary to provide a cake of high quality (Moncrieff, 1970). The 8' fats incorporate numerous, fairly small air bubbles in the batter, the intermediate fats produce a somewhat coarser air distribution and the 8 fats produce relatively few large air bubbles (Hoerr, 1960). Since the texture, by SEM, displayed little difference tnetween tallow samples and the volume and the tenderness of the baked products were consistent, this polymorphic 85 transformation is unlikely. Sensory_Eva1uation Sensory evaluation of the baked product revealed that all cakes performed equally well with significant differen- ces noted only for grain (Table 13). The cake prepared with original tallow had a poorer grain, rating 13.2 out of a possible 15, with the other samples rating 14.1, 14.6 and 14.4 for the 25°C solid tallow fraction, 35°C olein tallow fraction and control cake, respectively. This grain evalu- ation relates to the texture evaluation in determining the crumb characteristics. The opposition of results expressed could be due to the small sample size utilized in the texture evaluation and the inexperience of taste panel members. The cake prepared with the 35°C olein fraction tallow had the lowest flavor rating of 6.8 followed by the cake prepared with the 25°C solid fraction with a rating of 7.3, the original tallow cake with a score of 7.4 and the control cake with a score of 8.8. While differences in flavor scores were noted, these were not significant at the 95% level. All cakes were rated as equally acceptable by panel members obtaining a total score in excess of 84 out of a possible 100 points. The tallow cakes flavor scores in this investigation are somewhat lower than those reported by Bundy gt_ 1. (1981). Bundy and coworkers (1981) reported Amo.ovev oocoeoemwc pceorewcmem on mueowecw meme oEem xn oozoP—ow mceoe 86 ,. , one anEew one Louooca ”AmFTO area one xomv onenmpconm empecmmogexn .oomeeom ._o:ee wowep Lenses pnmwe mmcowpeoepeor Leo» row oPeom .FmIOP eonpmz .u.u.<.< no nomen< _.Fnee.em e.NHeP.nw N.Neem.em e.mnee.em oofi nere N.onem.m e.onen.m m.oeem.m N.onem.m o~ LOFOU naeco N.oeeo.m e.onem.m m.onem.m m.oeem.w OP mmocpwom m.onem.m~ m.oneo.NF n.0eefi.mr m.onem.m_ e_ mmoceoecon _.onem.m o.oeem.m N.oeee.m e.onem.m op mmmcpmvoe mnnpxoe m.oeen.er m.oee_.¢F —.~enm.m_ e.one¢.e_ or :weew n.0nen.w n.0eeo.m m.oeee.m N.oeem.m OF mrpez Co mmocxoenp m.onee.m m.oeee.m e.oeem.m o.Pnem.m or eNem n.0nem.e N.Peem.e m.oeem.e m.oeee.e OF. horseoerc: mFPmu ewe—o oomm UTFOm .oomm .3o__eo mcwnopconm o—nwmmoe Fecwmwco mpeeoeoeeoo Essexee movumweopoeeenu meowpoeem < .meowooeee goprep Coon oz“ one .zoppeu Fecwmweo meeeooconm _ewocoeeoo nee; ooeeeeee moxeo coxen open: ou<< mo moeoom exemcem .mp epnee 87 flavor scores of 8.9 and 8.1 for the 25°C solid tallow fraction cake and 35°C olein fraction cake, respectively. Both investigations utilized the same lot of dederized beef tallow, although Bundy and coworkers'(l981) investiga- tion was conducted approximately twelve months earlier. During the storage (4°C) of the tallow a stronger flavor could have developed, which could have resulted in the flavor scores experienced. The discrepancy in flavor scores also could be due to the individual panel members acuity for the tallow taste. A larger panel size in both of these investigations would have been preferred. Tallow Variability Beef tallow is not a uniform component but depends on the cattle from which it is obtained (Paul, 1972). The composition of the fat on any particular animal is affected by a variety of intrinsic and extrinsic factors. The difference can be attributed to breed, sire, sex and age of the animal and treatment influences of feed, exercise and stresses, as well as many other environmental conditions (Paul, 1972; Wilson, 1960). The possibility for larger variation in tallow characteristics exists which could have different functional properties in food systems. In the course of this investigation, four different tallow samples were utilized from three different processors over a period of one year. Bussey gt gt. (1981), Bundy 88 ‘_t gt. (l98l), DeFouw _t gt. (1981) and Ryan (1982) all utilized the same shipment of tallow from Stadler and Com- pany, Cleveland, Ohio. This shipment (2x400 165drums) was received in summer, 1979. The tallow used in the prepara- tion of white layer cakes also came from this source. Tallow samples were also received from Bungee Edible Oil. Corporation, Kankakee, Illinois, and Iowa Beef Processors, Nebraska. Samples were received in 50—60 lb drums during both winter and summer months. It was observed that the samples received during the winter and early spring months would not fractionate following the given procedure (Bussey _£.El-: 1981) and consequently appeared "harder" than the tallow received from Stadler and Co. It is speculated that feed variation could account for this observed difference. Early work on the effect of feed on body deposition fat in the bovine refutes the feed influence. Severn (1951) states that the body fat of cattle unlike that of swine is affected relatively little by the feed of the animal. Severn (1951) also reported that the environment of the animal appears to influence the composition of the fat, with warm temperatures tending to reduce the unsaturation. More recent work has looked at the carcass fat from cattle fed both high and low ratio fat diets, as well as different sources of fat. Dryden and coworkers (1973) reported that the type, and to a lesser extent, the amount of fat fed the bovine was effective in altering the type of 89 fatty acids deposited in the subcutaneous fat of the tail head region. Dryden and Marchello (1973) found that diets containing safflower oil at 6.0% caused the depot fat to be more unsaturated than the diets supplemented with 6.0% animal fat in the°bovine. Johnson and McClure (l972) reported that the addition of hydrogenated fat to the diet of the ruminant increased the proportions of oleic acid and decreased the polyunsaturated acids. In general, the addition of unsaturated dietary fats results in an increase in the degree of unsaturation of fatty acids in depot fat (Dryden and Marchello, l973; Dryden gt al., l973), whereas the addition of highly saturated animal fat has very little effect on the fatty acid composition of the body fat stores (Dryden _£._l., l973; Dryden and Marchello, l973; Johnson and McClure, l972). Cattle in the United States are generally grain fed (Swern, 1964). No mention is made of the availability of the cattle to graze, but it is speculated that grazing is occurring in the warmer months. The effect of grass vs corn feeding is speculated as the cause for the variability of tallow samples used in this investigation. Much of the success with the fractional crystallization process of beef tallow has taken place in Australia (Harald- son, l974). It is speculated that grazing of cattle is common in Australia and that the ratio of unsaturated to saturated fats is favorable for the fractional 90 crystallization process. In an attempt to substantiate this hypothesis, fatty acid profiles were compared for different lots of tallow (Table l4). It was found that there was a greater difference between the values reported for the same lot of tallow (Bussey t al., l981; DeFouw, l98l) than fatty acids from different lots of tallow. Table 9l l4. Fatty acid composition of original beef tallow from different sources and different seasons. Fatty acid Stadler and Co. Iowa Beef Bunge oil l 2 Processors , (summer) (winter) (summer) C14.0 ‘ 3.6 3.7 a a C16.0 24.1 29.16 26.58 27.4 Cl6tl 6.6 4.56 4.29 4.4 618.0 13.7 17.83 19.27 18.9 C18.1 50.1 44.75 47.33 46.8 C1822 - tr 1.40 2 4 Cl8t3 0.4 - 1.12 - 1reported by Bussey _t 31 (l98l) 2reported by DeFouw et al (l98l) anot reported SUMMARY AND CONCLUSIONS The functionality and utilization of beef tallow fractions obtained by aqueous fractionation of tallow was investigated in a three phase study. The quality of deep fat fried doughnuts was found to be equally acceptable using original beef tallow or either the 200 and 30°C olein fractions. ‘The doughnuts fried in a commercial soybean oil was found to be less acceptable than any of the doughnuts fried in the tallow frying media prin- cipally due to the low sensory flavor and fat absorption scores. Objective measurements on the oil and substrate revealed a low degree of oil degradation in the eight inter- mittent fryings of doughnuts, possibly due to the fresh fat added back to the fryers. Batter coated chicken wings were fried in 200 and 30°C olein fractions, original tallow and a commercial, soybean oil. The acceptability of the chicken wings was not found to be influenced by the original tallow or tallow fractions as frying media. Original beef tallow and tallow fractions were found to be more acceptable frying media than the commercial soybean oil in the deep fat frying of batter coated chicken wings. Objective measurements on the oil and substrate revealed a low degree of oil degradation in the 92 93 twelve intermittent fryings of chicken possibly due to the fresh fat added back to the fryers. The quality of A.A.C.C. White Layer Cakes was not adver- sely affected by the utilization of beef tallow as the shortening constituent when emulsifier was present. Sig- nificant deficiencies existed in the batter aeration proper— ties when original tallow or solid or olein fractions were utilized, but these deficiencies were not evidenced in the baked product. Dispersibility of the fat in the cake system was found to be greater and more uniform for all the tallow variables than the commercial shortening,.possibly due to the amount and type of emulsifier present in this system. The fractional crystallization process is not beneficial in producing fats and oils from beef tallow with equivalent acceptability to a commercial control. Original beef tallow has shown acceptability as a deep fat frying medium for doughnut and batter coated chicken wings and as a shortening in the preparation of white later cakes. PROPOSALS FOR FURTHER RESEARCH In the course'of this investigation several questions were raised which need addressing. These include: l. Feeding studies with cattle to determine if the degree of change in body deposition fat affects the fractional crystallization procedure. Pilot plant operations to inveStigate the large scale operation of deep fat frying using original beef tallow and/or beef tallow fractions as in a continuous potato chip frying operation. Cost analysis investigation of the efficiency of the fractionation procedure including energy, transportation, manpower and raw product cost among others. Determination of the polymorphic structure of the various tallow fractions and their use in shortening and margarine preparations. The cholesterol content of the various solid and olein fractions and their affect on human health. 94 APPENDICES 95 Appendix I Doughnut Score Card Sample # Name Date Points Score A. Tenderness very tender 1 moderately tender tender slightly tough very tough NbOWCDO 8. Fat Absorption no fat absorbed l slight fat absorption moderate fat absorption great fat absorption fat absorbed entirely mbowooo C. Crust Color optimum color - golden brown l slightly too light or too dark moderately too light or too dark very light or very dark pale or burned NDONCDO D. Flavor like very much I like moderately neither like nor dislike dislike moderately dislike very much meooo Comments: 96 Appendix II Chicken Score Card Sample # Name Date A. Crust Color optimum color — golden brown slightly too light or too dark moderately too light or too dark very light or very dark pale or burned 8. Fat Absorption no fat absorbed slight fat absorption moderate fat absorption great fat absorption fat absorbed entirely C. Tenderness very tender moderately tender tender slightly tough very tough D. Flavor like very much like moderately neither like nor dislike dislike moderately dislike very much Comments: Points NbONCDC) NDOWCDO N-DOWCDO N-DQCDO Score 97 Appendix III Layer Cake Score Card Sample # Name Date Points Score A. Cells (30 points) l. Uniformity (l0 points) (a) Even (normal) lO (b) Slightly_uneven 6 (c) Uneven 2 2. Size (10 points) (a) Dense (normal) lO (b) Close 8 (c) Slightly open 6 ____ (d) Open 4 3. Thickness of Halls (lO points) (a) Thin (normal) l0 (b) Slightly thick 6 ____ (c) Thick 2 8. Grain (16 points) l. Silky (normal) l6 2. Harsh l0 ____ 3. Coarse (cornbread) 8 C. Texture (34 points) 1. Moistness (lO points) (a) Gummy 6 (b) Moist (normal) lO (c) Slightly dry 8 ____ (d) Dry 4 2. Tenderness (14 points) (a) Very tender (normal) 14 (b) Tender l2 ____ (c) Slightly tough lO (d) Tough 4 3. Softness (l0 points) (a) Soft (normal) lO (b) Slightly firm 8 ____ (C) Firm 4 D. E. 98 Appendix III (cont'd.) Crumb Color (lO points) l. Acceptable . 2. Slightly unacceptable 3. Unacceptable Flavor (l0 points) l. Normal (no off flavors) 2. Slight off flavor 3. 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