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I” .'.I' 'IIIIIII‘.‘ IIIII'I IIIIIIIIIIII’I'IIIIIIIIIIIIIIII.I.‘ '1 r1 tiq's Ilium; Will Ll“ ll MI ii “iii“: 1| LIBRARY Michigan State University This is to certify that the thesis entitled BLACK PEPPER AROMA IN PLASTIC POUCHES presented by MASACHI KA UEDA has been accepted towards fulfillment of the requirements for 7W5. we} Dr. Hugh E. Lockhart Major professor Date June 6, 1979 0-7639 Return to Book drop to remove this checkout from your record. W 24 0 Mag" BLACK PEPPER AROMA IN PLASTIC POUCHES BY Masachika Ueda A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE School of Packaging 1979 ~¢ ABSTRACT BLACK PEPPER AROMA IN PLASTIC POUCHES BY Masachika Ueda In order to achieve cost reduction of a black pepper package, a plastic pouch was proposed. Aroma was the least stable factor in a black pepper storage test. So, it was assumed that the most critical factor for black pepper shelf life was its volatile oil loss. The critical volatile oil loss was predicted by a combination of a mathematical-experimental model and a sen— sory test. This result was confirmed by a chemical anal— ysis and another sensory test using an expert panel. These results indicated that the volitle oil loss was a critical factor and that it would be a reliable predictor of black pepper shelf life. By considering the critical volatile oil loss, it should be possible to develop plas- tic packages which will provide adequate shelf life for black pepper. ACKNOWLEDGMENTS The author wishes to express his sincere apprecia- tion and gratitude to the following individuals and organ— izations: Dr. Hugh E. Lockhart, Department of Packaging, under whose inspiring supervision and unselfish contribution of time and encouragement this research was completed. Dr. Steven W. Gyeszly, Department of Packaging, who served as a thesis committee member. To Dr. Gyeszly is owed a great deal of appreciation for his overall guidance in the field of permeability and shelf life. Dr. Jerry N. Cash, Department of Food Science, who, in addition to being a constant source of guidance in the field of food science, served as a thesis committee member. Dr. Jack R. Giacin, Department of Packaging, for time so graciously allotted for consultation and advice in the field of analytical aspects of packaging. Mr. Daniel J. Goeke Jr., whose valuable assistance in the field of spice science provided the author with the tools to accomplish this task. The Lion Dentifrice Co., Ltd., for granting educa- tional leave and their financial support during the course of study. ii TABLE LIST OF TABLES . . . LIST OF FIGURES . . INTRODUCTION . . . . LITERATURE REVIEW . THEORETICAL BASIS . OF CONTENTS Sensory Evaluation . Moisture Weight Prediction Model . . . Assumption for Volatile Oil Weight Change EXPERIMENTAL METHODS AND RESULTS Determination of the Total Weight Change (AWT) . . . Sensory Evaluation for Black Pepper Aroma Designing of the Sensory Test Procedure for the Triangle Test Determination of the Moisture Weight Change (AWm) . . . Determination of the Initial Moisture Content by a Mathe matical Determination of the Sorption Isotherm . Determination of the Permeability Constant Calculation of the Moisture Weight Change (AWm) . . . Calculation of (AWv.o.) . . Correlation Between Sensory Evaluation and Chemical Analysis Preparation of Black Pepper Specimens in M-24 Pouches Sensory Test for Pepper Aroma by the Vol til Inexperienced Panels iii Oil Weight Change C Page vii 10 10 12 17 18 18 19 19 21 24 24 25 29 29 32 32 34 34 Page Sensory Test for Pepper Flavor by Experienced Panels . . . . . . . . . . . 35 Chemical Analysis for Volatile and Non-Volatile Oil . . . . . . . . . . . . 37 DISCUSSION . . . . . . . . . . . . . . . . . . . . . 40 Consideration of the Assumptions Used in the Mathematical Model . . . . . . . . . . . . . 40 Discussion of the Experimental Results . . . . 44 Consideration of the Critical Volatile Oil LOSS . O O O O O O O O O O C O O O O O O O O 49 Consideration of Moisture Effect . . . . . . . 52 Error Analysis . . . . . . . . . . . . . . . . 54 CONCLUSION . . . . . . . . . . . . . . . . . . . . . 61 Future Work . . . . . . . . . . . . . . . . . 61 SUMMARY . . . . . . . . . . . . . . . . . . . . . . 63 APPENDICES . . . . . . . . . . . . . . . . . . . . . 65 A. TABLES FOR SIGNIFICANCE IN THE TRIANGLE TEST AND IN THE PAIRED TEST . . . . . . . . . . . . 65 B. THE DERIVATION OF EQUATION (4) . . . . . . . . 67 C. THE DERIVATION FROM FICK'S LAW AND HENRY'S LAW TO EQUATION (5) . . . . . . . . . . . . . 59 D. THE DERIVATION OF EQUATION (7) . . . . . . . . 72 E. SENSORY TEST FOR PEPPER FLAVOR: COOKING PROCEDRUE FOR THE MEDIA AND SERVING PROCE- DURE . . . . . . . . . . . . . . . . . . . . . 74 F. VOLATILE OIL CONTENT OF BLACK PEPPER BY STEAM DISTILLATION . . . . . . . . . . . . . . . . . 75 G. NON-VOLATILE OIL OF BLACK PEPPER DETERMINED BY SOLVENT EXTRACTION . . . . L . . . . . . . 77 REFERENCES . . . . . . . . . . . . . . . . . . . . . 78 iv 10. ll. 12. 13. LIST OF TABLES Page The Main Requirement for a Black Pepper Package . . . . . . . . . . . . . . . . . . . . 2 Specification for Black Pepper . . . . . . . . 3 The Critical Factors for Adequate Sensory Evaluation . . . . . . . . . . . . . . . . . . 11 The Weight Change of Black Pepper in Plastic Pouches . . . . . . . . . . . . . . . . . . . . 20 Sensory Test Results for Black Pepper Aroma in LDPE Pouches (Triangle Test) . . . . . . . . 25 The Initial Moisture Content of Black Pepper . 26 The Salt Solutions and Equilibrium Moisture Content of Black Pepper . . . . . . . . . . . . 27 The Intercept (a) and SlOpe (b) of the Sorption Isotherms for Black Pepper . . . . . . . . . . 27 The Water Vapor Transmission Rate (WVTR) and Permeability Constant (P) of Films . . . . . . 29 The Moisture Weight Change of Black Pepper in Plastic Pouches (AWm) Using a Mathematical I'IOdel o o o o o o o o o o o o o o o o o o o o o 32 The Volatile Oil Weight Change (AWv.o.) and the Sensory Test Results of Aroma for Black Pepper in Plastic Pouches . . . . . . . . . . . . . . 33 Sensory Test Results for Black Pepper Aroma in M-24 Pouches with IneXperienced Panels (Triangle Test) . . . . . . . . . . . . . . . . 36 Sensory Test Results for Black Pepper Flavor in M-24 Pouches with Expert Panels (Paired Comparison) . . . . . . . . . . . . . . . . . . 36 Table 14. 15. 16. 17. 18. 19. 20. Page The Chemical Analysis Results of Volatile and Non-Volatile Oil for Black Pepper . . . . . 39 The Effect of Temperature (T) Fluctuations on the Moisture Weight Change (AWm) of Black Pepper . . . . . . . . . . . . . . . . . . . . 55 The Effect of Relative Humidity (RH) Fluctua- tions on the Moisture Weight Change (AWm) of Black Pepper . . . . . . . . . . . . . . . . . 57 The Effect of Permeability Constant (P) Dif- ference on the Moisture Weight Change (AWm) of Black Pepper . . . . . . . . . . . . . . . . . 58 The Effect of Film Thickness (l) Variation on the Moisture Weight Change (AWm) of Black Pepper . . . . . . . . . . . . . . . . . . . . 58 Maximum Erros in AWm by the Effect of A, V, W, and b O O O O O O O O O O I O O O O O O O O 0 O 59 Table for the Significance in the Triangle Test . . . . . . . . . . . . . . . . . . . . . 65 Table for the Significance in the Paired Test . 66 vi Figure 1. LIST OF FIGURES Triangle Test Design Sheet . . . . . . . . . The Report Form of the Triangle Test . . . Sorption Isotherms of Black Pepper . . . . . The Ballot for Black Pepper Flavor (Paired Comparison Test) . . . . . . . . . . . . . Black Pepper Aroma VS. Volatile Oil LOSS . . Revised Sorption Isotherms for Black Pepper vii Page 22 23 28 38 51 53 I NTRODUCT ION Packages for black pepper are mostly glass bottles and metal cans. Plastic pouches can be marketed for reasons of cost reduction and resource conservation. The cost of a glass bottle (1.75 02), a cap and labels is estimated at 7.4¢. A printed metal can (4 oz) is estimated to cost 10.l¢.65 Compare these costs with the cost of a preprinted 18 The filling and closing cost pouch estimated at 0.74¢. with glass bottles or metal cans is also more than the filling and closing cost with form fill sealed plastic 63 In this study, a plastic pouch is considered pouches. a refill package, not intended for dispensing. If plastic pouches are used as refill packages, this eliminates the need for glass or metal packages, which results in re— source conservation to the extent that the overall cost of the plastic is cheaper in terms of energy required to make, ship and use. The market of black pepper is not small, which makes this cost reduction more attractive. In re- cent years, the average annual world exports of pepper have amounted to about $38.5 million, or just over 25 percent of the total volume of net world exports of all spices.53 The main requirements for black pepper packages are given in Table 1. Protection of black pepper against certain environments is essential for adequate Shelf life. The other factors in Table 1 must be established during packaging development, but only the protection function is considered in this study. Table l. The Main Requirement for a Black Pepper Package 1. Safety as a food package 2. Product quality protection against the following en- vironments A. Chemical Environment Volatile Oil permeation and chemical reaction Non-volatile Oil permeation and chemical reaction Moisture effect B. Physical Environment Light Shock, vibration and compression C. Insect and Microbiological Environment 3. The least possible cost 4. Communication to consumers (convenience, labeling, and appearance) 5. Containment function 6. Disposability Black pepper, Piper nigrum E., has two characteris— tics which affect the quality. One is the aromatic odor contributed by an essential oil. This essential oil con- 46 tains these compounds: a-pinene, B-pinene, and limonene. The essential Oil is commonly referred to as volatile oil. The other characteristic is the sharp pungent taste con- tained in the Oleoresin, which consists of piperine, chavi- 53 These are referred to as non- cine and piperidine. volatile oil. The Food and Drug Administration (F.D.A.)68 and the American Spice Trade Association (A.S.T.A.)2 specify a standard of identity for black pepper. It is given in Table 2. This standard lists volatile oil and non-volatile Oil along with other elements. The maximum moisture con- tent is specified in the regulation because microbial spoilage readily occurs when the moisture exceeds twelve percent. This can be considered in water sorption iso- therm of black pepper. The other factors, ash, acid in- soluble ash, and crude fiber, are considered as the second- ary concern for black pepper shelf life because they are more stable than the primary concern: volatile and non- volatile oil. Table 2. Specification for Black Pepper* VOlatile Oil Min 2.0 m1/100g Non-volatile Oil Min. 7.0% (Methylene Chloride) Moisture Max. 12.0% Ash Max. 7.0% Acid Insoluble Ash Max. 1.0% Crude Fiber Max. 11.0% *U.S. Food and Drug Administration, Food and Drug NO. 2, 1962. The effect of light should be considered for trans- parent plastic pouches. Wrolstad et al.71 reported that light causes certain photochemical changes that are evi- denced by a decrease in at least one fraction of volatile oil, and an increase in another. Their experimental method was with direct sunlight exposure for seven weeks. In real life, black pepper is exposed to fluorescent light in super- markets, but not to sunlight. Therefore, their experi— mental method can be considered too stringent and prob- ably not applicable. The fluorescent light effect was con- sidered in earlier work and found to be negligible.66 Another factor is insect and microbiological spoilage. Several leading spice processors exercise quality control programs to assure themselves and their industrial con- sumers that their spices are microbiOlOgically acceptable.56 For this reason, the insect and microbiological spoilage consideration is eliminated from this study. Considering these factors, volatile oil and non- volatile oil are the primary concern for black pepper Shelf life in plastic pouches. The effect of moisture for black pepper shelf life can be considered in water sorption iso- therm. LITERATURE REVIEW According to the Food Stability Survey by Rutgers University in 1971, the shelf life of ground black pepper in a metal can is three years.56 They also reported that quality loss factors for black pepper during storage were aroma and flavor. It is well known in the spice industry that aroma and flavor are contributed by volatile and non— 53 volatile oils. Comparing these volatile and non-vola- 74 reported tile oils in a stability test, Yugami et al. that the critical factor for black pepper shelf life was the volatile oil, rather than the non-volatile oil. This implies that the non-volatile oil is more stable than the volatile oil. Using gas chromatography he found that black pepper in a metal can, stored for 3 months at 400C, lost its volatile Oil constituents: a-pinene and B-pinene due to the relatively low boiling points of these com- pounds. He also reported that the top note* Of the pepper aroma was diminished after the storage. The volatile oil conposition of black pepper has been 22 studied by several investigators. Hasselstrom et al. isolated the monoterpenes. Using gas chromatogrraphy and *TOp note: Initial intensity ** RH Test 8/9 8/10 6/10 6/11 22/22 0 Ratio of 100 F Correct 11/24 12/24 15/24* -- 19/24** Replies 53'7% contr°l> 9/11 8/12 13/15* -- 18/19** Test *Significance at 99% Confidence Level **Significance at 99.9% Confidence Level Control> test: Ratio that the control aroma was found to be stronger than the stored sample aroma. no weight change was noticed. The results, expressed in g/lOOg-dry product, and in g/lOOg-product, are in Table 6. Determination of the Sorption Isotherm The sorption isotherm was determined by using satur- ated salt solutions in contact with excess undissolved crystals. At constant temperature, the solutions main- tain constant humidities in closed containers.7o Approx- imately 1.5 g of each black pepper were weighed into alum- inum dishes then placed into containers where the salt 26 Table 6. The Initial Moisture Content of Black Pepper Initial Moisture Content Sample NO dry basis wet basis (9/1009°dry product) (g/lOOg-product) 1 6.87 6.43 2 6.77 6.34 3 6.69 6.27 4 6.45 6.06 5 6.52 6.13 R 6.660 6.246 S 0.155 0.135 solutions were set. The containers were stored at 75°F (average) and at 1000F. The black pepper samples were periodically weighed until they reached equilibrium. The averages of three-replication results expressed in unit of g/lOOg-dry product, are given in Table 7. From the equi- librium moisture content in Table 7, the sorption isotherms for the black pepper were drawn in Figure 3. As shown in Figure 3, the sorption isotherms were fitted by straight lines within the range of 30% to 70% RH with reasonable accuracy. The straingt lines were de- termined by linear regression analysis, and their inter- cepts and slopes are given in Table 8. 27 Table 7. The Salt Solutions and Equilibrium Moisture Content of Black Pepper 0 0 Salt* 75 F 100 F Solution 9/1009° 9/1009’ % RH dry product % RH dry product (NH4)ZSO4 80.6 10.679 79.5 10.385 NaCl 75.5 9.349 75.6 8.181 NaNO2 65.3 7.424 62.0 6.254 NaBr 58.5 6.619 53.7 5.154 Mg(NO3)2 53.5 6.246 -- -- KNO2 49.0 5.831 46.5 4.486 KZCO3 -- __ 43.0 3.984 MgCl2 33.0 4.404 32.0 2.912 *Wink and Sears, 1950. Table 8. The Intercept (a) and Slope (b) of the Sorption Isotherms for Black Pepper a (g/lOOg-dry b (g/lOOg-dry Temperature product) product/%RH) O 75 P 1.315 0.0925 100°P -0.655 0.1096 28 g/lOOg-dry product 124 O at 75 F: A at 1000F: o 4 C) 10- j I. 1!: .’I I! I :e: 8.. u 1.315 + a 0.0952 Hi 8 C O U 6 6" -0.655 + 3 0.1096 Hi 4.) U} -H O 2 4-4 2‘ T T 1 l 1 0 20 40 60 80 100% Relative Humidity (Hi) Figure 3. Sorption Isotherms of Black Pepper 29 Determination of the Permeability Constant Water vapor transmission rates of LDPE and M-24 were determined by the dish method with desiccant, which is de- scribed in ASTM E96—66, Procedure A. These rates were con- verted to permeability constant, expressed in g-mil/cmz/ hour/Aatm. The averages of three-replication results are given in Table 9. Table 9. The Water Vapor Transmission Rate (WVTR) and Permeability Constant (P) of Films WVTR P 2 . 2 g/cm /hr g'mil/cm /hr/Aatm o -5 -4 78 F M-24 0.4285 x 10 M-24 1.407 x 10 78°F 47% RH LDPE 1.2010 x 10'5 LDPE 7.890 x 10"4 100°F M-24 2.8013 x 10"5 100°F M-24 2.707 x 10'4 80% RH LDPE 7.0625 x 10'5 LDPE 13.650 x 10"4 Calculation of the Moisture Weight Change (AWm) AWm can be calculated from Equations (14) and (8). AWm = (96%-+ i§53%;¥) (He - (He —Hi(0) e'J'“ - Hi(0)) (l4) . _ PFA'PS 3 ’ 1 (I8 Ps-V/R-T + BTW) (8) 30 The following variables were obtained from the experiment. W = 1.3 g . _ (cc) (atm) R 15 the gas constant - 82.05 (0K) (moles) 2 A = 40 cm Hi(0) = 44% T = 298.0 °K (77°F), T = 310.8°K (100°F) 9 Ps 0.03126 atm (77°F)°9, P5 = 0.06468 atm (100°F)6 He = 58.5% (77°F),He = 53.7% (100°F) The thickness was measured and found to vary : 10% or less. 2 = 1 i 0.1 mil (LDPE), 2 = 0.5 i 0.05 mil (M-24) The headspace volume (V) was estimated because this value is small and is not so critical in Equations (14) and (8). V = 8 cc The permeability constant (P) is Obtained from Table 9. However, since the room temperature was 78°F during WVTR measurement, P (at 78°F) should be converted to P (at 77°F). By using Arrhenius Equation40 = Po-e-B/T (16) PI Where Po is the permeability constant (independent on tem- perature), and B is the constant. Plug P and T results (from Table 9) into Equation (16). For M-24 4 — .e-B/298.56 1.407 x 10' = PO (17) 31 '8/310°78 2.707 x 10'4 = Peas (18) Solve Po and B from Equations (17) and (18) PO = 2362.3 6 = 4966.85 SO, Equation (16) becomes -4966.85/T P = 2362.3e (19) For LDPE using the same manner, -4154.87/T P = 872.8e (20) Therefore, when T = 77oF = 296.9OK P (ll-24) 1.364 x 10..4 g-mil/cmZ/hr/Aatm P (LDPE) 7.690 x 10'4 g-mil/cmz/hr/Aatm When T = 100°F 310.8°K P (M—24) 2.71 x 10‘4 g'mil/cmz/hr/Aatm 13.65 x 10‘4 g'mil/cmz/hr/Aatm P (LDPE) From Table 8 the SlOpe of sorption isotherm, b, can be Ob- tained. However, the room temperature was 75°F, so b (at 750E) should be converted to b (at 77°F). By using propor- tional allotment, x 77-75 100-75 b(at 77°F) 0.0925 + (0.1096 - 0.0925) 0.0939 g/lOOg-dry product/% RH, and b(at 1000F) = 0.1096 g/lOOg°dry product/% RH. From all of the above inputs, AWm can be calculated in Equation (14). The results are given in Table 10. 32 Table 10. The Moisture Weight Change of Black Pepper in Plastic Pouches (AWm) Using a Mathematical Model AWm(g/100g°dry product) 26 hr 61 hr 84 hr 122 hr 146 hr M-24 .125 .277 .372 .511 .595 77°F LDPE .331 .674 .859 1.094 1.213 o M—24 .316 .623 .779 .968 1.055 100 F LDPE .664 1.007 1.212 1.318 1.348 Calculation of the Volatile Oil Weight Change (AWv.O.) By using Equation (15) AWv.o. can be obtained since ANT is given in Table 4 and AWm is given in Table 10. The results are given in Table 11 comparing with the sensory test results for black pepper aroma. Correlation Between Sensory Evaluation and ChemIcal AnaIysiS In this study, it was assumed that the shelf life of black pepper in plastic pouches was determined by the crit- ical volatile oil loss. The volatile oil weight change was calculated in Equation (15) and the critical aroma loss was determined by the sensory test. However, there are two questions concerning this approach. First, even though Yugami et al.74 reported that the volatile oil loss is the 33 Table 11. The Volatile Oil Weight Change (AWV.O.) and the Sensory Test Results of Aroma for Black Pepper in Plastic Pouches AWv.0. (g/IOOg-dry product) 26 hr 61 hr 84 hr 122 hr 146 hr 77°F M-24 .030 .108 .126 .125 .109 58.5% LDPE .058 .141 .189 .254 .345** 100°F M-24 .087 .112 .124 .086 .005 53.7% LDPE .158 .286 .499* .599S .687** *,**: Sensory test results showed that the aroma of the stored sample was significantly weaker than the aroma of the control at 99% confidence level (*), and at 99.9% confidence level (**). S: Sensory test was not conducted for this sample. most critical factor for black pepper shelf life, the vola— tile oil affects only the aroma of black pepper, not its flavor. In other words, the pepper's taste might not be acceptable even when the volatile oil loss is still accept- able. Therefore, the flavor Of black pepper should be tested by a sensory test after a certain storage period. Secondly, the volatile oil weight change, obtained from Equation (15), was based on several assumptions. It is desirable, therefore, to confirm the results by other meth- ods (e.g. chemical analysis). Considering these factors, the following experiments were designed and conducted. 34 Preparation of Black Pepper Specimens in M-24 Pouches Ground black pepper in a 4 oz can, packaged on De— cember 19, 1978, was used. The variety of this black pep- per was a combination of Lampong and Brazilian. The black pepper weight was between 1.4 g and 1.5 g, and was packed in 0.5 mil M-24 pouches. These pouches were four Side im- pulse sealed with dimensions 4 cm x 5 cm. Sensory Test for Pepper Aroma by Inexperienced Panels The prepared specimsns were stored at 75°F, 50% RH (average) and 100°F, 80% RH. After certain storage periods, the specimens were transferred into 22 cc amber Boston round glass bottles. Each bottle contained 0.5 g of ground black pepper and the bottles were closed with caps. Also 0.5 g of black pepper used as a control was prepared from an unopened can which had the same manufacturing code as the experimental pepper. Three replications of the storage sample and three replications of the control were coded randomly. Three samples, a combination of the stored sample(s) and the control(s), were presented to each panel- ist. Aeoording to the triangle test design in Figure 1, twenty-four panelists tested the same set in different coding combinations and orders. The report form, given in Figure 2, was used. Total correct numbers were counted, and the significance in aroma difference was determined by Table 20 in Appendix A. The panelists also answered a question: which sample(s) has (have) stronger odor? Since 35 this was the paired comparison test, Table 21 in Appendix A was applied to determine any significant differences. These results are given in Table 12. Table 12 shows that there was a significant differ- ence between the aroma of the control and the aroma of the sample which was stored at 100°F, 80% RH for five weeks or longer. However, there was no significant difference be- tween the aroma Of the control and the aroma of the sample which was stored at 75°F, 50% RH for less than nine weeks. The following two experiments were designed based on these results. Sensory Test for Pepper Flavor by Experienced Panels The black pepper in M—24 pouches stored for seven weeks at 100°F, 80% RH and 75°F, 50% RH, was used. Here, the stored sample at 100°F, 80% RH represented the black pepper whose aroma was found to be significantly different from the control aroma by the triangle test. On the other hand, the stored sample at 75°F, 50% RH represented the black pepper whose aroma was found to be not significantly different from the control aroma. The sensory evaluation for black pepper flavor (the paired comparison test) was conducted in a spice company.* Both stored samples were *Both sensory test and chemical test were conducted in laboratories of the spice company. The sensory panel- ists were trained in the spice company for evaluation of Spice. The name of the company is not disclosed here, but it is available upon the personal contact with the author. 36 Table 12. Sensory Test Results for Black Pepper Aroma in M-24 Pouches with Inexperienced Panels (Triangle Test) Stored 2 5 7 9 Condition weeks weeks weeks weeks 0 Ratio of correct 75 F replies 9/24 11/24 -- 7/24 50% RH Control> test 5/9 3/11 -- 3/7 0 Ratio of correct * ** __ 100 F replies 11/24 15/24 17/24 80% RH Control> test 2/11 4/15 4/17 -- Control> test: Ratio that the control aroma was found to be stronger than the stored sample aroma. *Siginficance at 99% confidence level. **Significance at 99.9% confidence level. Table 13. Sensory Test Results for Black Pepper Flavor in M-24 Pouches with Expert Panels (Paired Comparison Test) Stored Initial Pepper Pepper Total Pepper Condition Flavor Heat Flavor 75°F 50% RH 8/23 11/24 9/24 100°F 80% RH 16/24 19/24* 16/24 Figures are the ratio that the control was found to be stronger than the stored sample. *Significance at 99% confidence level. 37 compared directly to the control in two separate tests on the same day. For each test, the samples were evaluated in potato soup media by twenty-four experienced panelists. The ingredients of the potato soup media, the cooking pro- cedure, and the serving procedure are given in Appendix E. The ballot used in the paired comparison test is in Figure 4. These results are given in Table 13. Chemical Analysis for Volatile and Non-Volatile Oil The black pepper in M-24 pouches stored for seven weeks at 100°F, 80% RH and 75°F, 50% RH was presented to a spice company.* They analyzed the volatile oil content by the steam distillation method Specified in the standard of the American Spice Trade Association.6 The non-volatile Oil was determined by the solvent extraction method. These procedures are in Appendices F and G. The results are given in Table 14. 38 NAME DATE BLACK PEPPER FLAVOR Please try these two samples from left to right and answer the following questions: 1. Which sample has more initial flavor (the charac— teristic initial flavor which occurs before the throat heat)? Is the difference in initial flavor: Slight Moderate Strong 2. Which sample has more heat? __» Is the difference in heat: Slight Moderate _ Strong 3. Which sample has more total pepper flavor (initial flavor plus heat)? Is the difference in total flavor: Slight Moderate _ Strong _ THANK YOU! Figure 4. The Ballot for Black Pepper Flavor (Paired Comparison Test) 39 Table 14. The Chemical Analysis Results of Volatile and Non-Volatile Oil for Black Pepper Stored NO Volatile Oil Non-Volatile Oil Condition ' (ml/lOOg'product) (g/lOOg-product) O 75 F l 2.33 7.98 50% RH 2 2.32 7.98 Y 2.325 7.98 O 100 F l 2.17 7.91 80% RH 2 2.17 7.79 8 2.17 7.85 The samples were stored in M-24 pouches for 7 weeks. DISCUSSION The shelf life of black pepper was assumed in the study to be determined by the critical volatile Oil loss. The critical volatile oil loss was obtained by a combina- tion of the calculation-experimental method and sensory evaluation using the triangle test. These results were compared with the chemical analysis results and the sen- sory evaluation results with experienced panels. Before discussing the experimental results, several assumptions which were made for the mathematical model are considered. Consideration of the Assumptions Used in the Mathematical Model Several assumptions were made in the section labeled Moisture Weight Prediction by a Mathematical Model in the chapter on Theoretical Basis. Unless these assumptions are valid, we cannot use Equation (15) for volatile oil weight loss. The following is a discussion of the assump- tions. The permeability constant was assumed to depend only on temperature, not on wall thickness or pressure differ— ence. The effect of material thickness on a permeability constant has been discussed by many investigators. SCOpp 40 41 et a1.58 in 1958 and Briston6 in 1970 reported that the permeability constant is not independent of the material thickness. However, they used material ranging from one to twenty mils thick. All other investigators referenced in this Study tested a range from one to five mils and found no dependence of permeability constant on material thickness. In this study, 0.5 mil and 1 mil films were used. SO, the effect of permeability constant is consid- ered to be independent of material thickness. The effect of pressure difference was also dis- cussed in several works. Barrer4 in 1951 and Briston6 in 1970 noted in their work that in hydrophilic materials there existed a strong dependence of the solubility coef— ficient upon partial pressure differential when exposed to water vapor. In this study, the weight changes of LDPE and M-24 films were tested and found to be negligible. This indicates that the films are not hydrophilic. There- fore, the permeability constants of these films are inde- pendent Of the partial pressure difference. It was assumed that the temperature was constant and was the same inside and outside of the package, and the outside relative humidity was constant. These assumptions may not be exactly true. However, laboratory records in— dicated that during the period Of test, fluctuations of temperature and humidity were small and regular. There- fore, the variations can be ignored. We did not consider mass interchange between outside 42 and inside environments by flow. With packaging materials, mass flow occurs through pinholes, cracks, and discontinu- ous seals. With modern materials, pinholing or cracks and discontinuous seals, which lead to mass flow, are considered to be defects. These defects were eliminated by care in selection of materials and construction of pouches. It was assumed that moisture in the product and water vapor in the headspace are always in equilibrium. This is true when permeation through a film is slower than dif- fusion into a product. In this study LDPE and M-24 films were used, and both have relatively low permeability con- stants against water vapor. Permeation was assumed to be a steady state process. There is a lag time before reaching a steady state process, and the lag time can be calculated in Equation (21)63 6D where L is the lag time, 2 is the film thickness, and D is the diffusion coefficient In this study, 1 mil LDPE and 0.5 mil M—24 were used. The literature values for diffusion coefficients of LDPE and M-24 films against water vapor are about 0.2 milz/min and 0.02 milz/min. Plugging these data into Equation (21), we can obtain L = 0.8 min (LDPE) and L = 2.1 min (M-24). Therefore, the time lags can be ignored. 43 It was assumed that there were no chemical reactions among product, package and environment. There is a possi— bility for volatile oil in black pepper to interact with a film. The volatile oil would act as a plasticizer, and increase the permeability Of the film. This problem must be left for future study. Since LDPE and M-24 were rela- tively inert against volatile oil,66 and the storage period was only one week, the mathematical model can be assumed to be valid in this study. The Ideal Gas Law was assumed to be applicable to water vapor. There are no real gases which obey the Ideal Gas Law. Van Der Waal's Equation represents the behavior Of ordinary gases more correctly than the Ideal Gas Law. However, Van Der Waal's Equation is more complicated and the error introduced by using the Ideal Gas Law is consid- ered to be negligible.12 It was assumed that the wall thickness of a package and headspace volume were constant. This assumption will be validated by error analysis in a later section. We assumed that the sorption isotherm was fitted by a straight line within a certain range. From Figure 3, it can be found that the experimental results were on straight lines within the range of 30 to 70% RH with good agreement. Considering all of the above assumptions, the model was concluded to be valid with its error analysis. 44 Discussion of the Experimental Results The purpose of the experiment was to Obtain the crit- ical volatile Oil loss. For this reason, the validity Of Equation (15) is essential. AWT = AWm + AWv.o. (15) This equation is valid when the weight change of the pack- age is negligible. The weight change Of LDPE and M-24 films were less than 0.0004g in any storage conditions. This satisfies the condition for Equation (15), that is, the weight change of the film is negligible. In Table 4, we can find that AW at 77°F, 58.5% RH T (0.486g/100g-dry product) was smaller than AW eat 100°F, T 53.7% RH (1.0509/lOOg-dry product) in M-24 pouches while AW at 77°F, 58.5% RH (0.8689/100g-dry product) was larger T than AW at 100°F, 53.7% RH (0.6619/lOOg-dry product) in T LDPE pouches after seven days storage. The results in M-24 pouches can be explained by the permeability constant (P) and the saturated partial pressure (PS). Table 9 shows that P for M—24 at 100°F is about double P at 78°F. This means that twice as much water vapor can penetrate through M-24 film at 100°F as at 78°F. The saturated partial pres- sure (Ps) at 100°F is also larger than Ps at 77°F. So, the results in Table 4 can be explained as follows: AW at T 100°F, 53.7% RH gained more moisture than AW at 77°F, T 58.5% RH because of the higher P and P5. In the case of LDPE pouches, P at 100°F was also about double P at 78°F. 45 However, AW at 100°F, 53.7% RH was even smaller than T AWT at 77°F, 58.5% RH. This can be explained by the fol- lowing: black pepper lost something at 100°F, 53.7% RH. We assumed it was a volatile Oil. These results had an im- portant meaning in this study. That is, the weight change of volatile oil can be measured by an analytical balance with a reasonable sensitivity. In order to calculate AWm, the initial moisture con- tent, the equilibrium moisture content, and the water vapor transmission rate were measured. Table 6 shows the initial moisture content results by the P205 method. Actually, these results are not only the moisture loss, but also the volatile oil loss. 80, some correction is necessary in order to use these figures. There was the same problem in the measurement of the equilibrium moisture content (the salt solution method). The results in Table 7 are the sum of the moisture weight change and the volatile Oil loss. In both the P205 method and the salt solution method, the black pepper samples in aluminum dishes were stored for more than twenty days. It was noticed that the aroma of the pepper was totally gone after the storage. In other words, the volatile oil might be completely dimin- ished in both experiments. Since the same amount and the same origin of black pepper was used in both measurements, it is reasonable to assume that the same amount of vola— tile oil was missing. In Figure 3, the sorption isotherms for black pepper are drawn. The isotherms were obtained 46 from the initial moisture content measurement and the equilibrium moisture content measurement. So, the iso- therms are the sum Of the moisture weight change and the volatile Oil loss. Since we assumed that the same amount of volatile oil was lost in all relative humidity condi— tions, the actual water sorption isotherms would be parallel to the sorption isotherms drawn in Figure 3. This means that the slopes of the actual water sorption isotherms are the same as the SlOpeS in Figure 3. Therefore, we can use the same slope (b) in Equation (14) for the AWm calculation. The critical volatile oil loss can be determined in Table 11. From the table, the significant aroma differ- ences will be found when AWv.o. is more than 0.345 g/100g- dry product, and the significant aroma differences will not be found when AWv.O. is less than 0.286g/lOOg'dry pro- duct. SO, the critical volatile Oil loss will be between 0.286 and 0.345g/lOOg'dry product. To confirm the critical volatile oil loss, two other experiments were conducted. One was the sensory test for pepper flavor with experienced panels. The other was the chemical analysis to confirm the critical volatile oil loss. Table 12 shows the sensory test results for black pepper aroma with inexperienced panels. In the table, the aroma of black pepper, stored in M-24 pouches for seven weeks at 100°F, 80% RH, shows a significant difference from the aroma of the control. However, the aroma of black pepper, stored in M-24 pouches at 75°F, 50% RH for the 47 same period, does not Show a Significant difference from the aroma of the control. Using these two samples, the paired comparison test for the pepper flavor was conducted with experienced panels. The results in Table 13 show that in one important factor there was a significant difference between the control and the sample. The pepper heat* of the control was found to be significantly stronger than the pepper heat of the sample stored at 100°F, 80% RH. This result has two meanings. First, this result for fla— vor is pretty much the same as the triangle test result for aroma. The pepper heat of the stored sample at 100°F, 80% RH was found to be significantly different, and the pepper aroma of the same sample was also found to be sig- nificantly different at the same storage period. Secondly, the significance in the pepper heat might be a symptom of total pepper flavor deterioration in the future. The fact that total pepper flavor was not found significant for either sample supports the hypothesis that the aroma test should be a reliable predictor of total flavor. V The results of the chemical analysis for volatile oil and non-volatile oil are given in Table 14. There was a difference in the amount of volatile oil between the pepper stored at 75°F, 50% RH (2.325 ml/lOOg'product) and the pepper stored at 100°F, 80% RH (2.17 ml/100'product). There might be a difference in the amount of non-volatile *Pepper heat: Hot taste after the initial flavor. 48 oil between the pepper stored at 75°F, 50% RH (7.98 g/lOOg° product) and the pepper stored at 100°F, 80% RH (7.85g/1009- product). However, the sample stored at 100°F, 80% RH showed a large range so that we cannot conclude a signifi- cant difference between these two stored samples. Three conclusions can be drawn from the results in Table 14. First, the critical volatile oil loss can be calculated. The average volatile Oil in pepper is 2.5 m1/100g, and the specific gravity of the volatile oil is 0.9.53 SO, the weight loss at 75°F, 50% RH storage is (2.5 - 2.325) x 0.9 = 0.157 g/100goproduct The weight loss at 100°F, 80% RH storage is (2.5 - 2.17) x 0.9 = 0.297g/100g'product The critical volatile oil loss is between 0.157 and 0.297 g/lOOg-product. In Equation (15) we also obtained the critical volatile Oil loss between 0.286 and 0.3459/1009- dry product. However, we cannot compare these results directly because the units were different. The unit con- version will be shown later in this study. The second conclusion from Table 14 is the possibil- ity of non-volatile Oil weight change. The weight change of the non-volatile Oil cannot be concluded from Table 14 because of the large range of data. However, if there ex- ists a non-volatile oil weight change, Equation (15) must be changed to AWT = AWm + AWv.o. + AWn.v.o. (22) 49 where AWn.V.O. is the weight change of the non-volatile Oil. This upsets the original hypothesis: The measurement of volatile Oil loss, and thus aroma loss, is the most criti- cal factor in black pepper shelf life. Since this is an important factor, it should be left for future study. This is also true; AWv.O. > AWn.v.o. however, we do not know by how much AWv.o. is larger than AWn.v.o. The third conclusion is that the results in Table 14 are all within the limits specified by the F.D.A. and A.S.T.A. (Table 2). This indicates that the sensory test is more stringent than the chemical analysis. Consideration of the Critical Volatile Oil Loss The values for critical volatile oil loss were Ob- tained from the chemical analysis and Equation (15). They also have different dimensions. In order to unify both units, the actual initial moisture content should be de- termined. From Table 6 the initial moisture content is 6.246 g/lOOg-product. This value includes the moisture loss and the volatile oil loss. We made the assumption that all volatile oils were diminished. Since the specific gravity of the average volatile Oil is 0.9 and pepper con- tains 2.5 ml/lOOg-product volatile oil, the actual initial 50 moisture content can be calculated. Initial Moisture Content = 6.246 + (2.5 x 0.9) = 8.509/1OOg-product. Therefore, the volatile oil loss by chemical analysis can be 0.157 e (1-0.085) 0.172g/100godry product (at 75°F, 50% RH) 0.297 % (1-0.085) 0.325g/100g:dry product (at 100°F, 80% RH) Comparing these figures to the sensory test results, the aroma of the sample stored at 100°F, 80% RH was found to be significantly different from the aroma of the control. SO, the critical volatile oil loss is 0.3259/lOOg°dry pro- duct or less. This result satisfies the predicted critical volatile oil loss range, 0.286 to 0.34Sg/100g-dry product. From all of the above discussions, the relationship between the volatile oil loss and the black pepper aroma can be concluded. The range for critical volatile oil loss was found to be 0.28 to 0.35g/100g-dry product. The relationship between the aroma and AWv.o. is drawn in Fig- ure 5. The graph is a discontinuous curve because the pepper aroma cannot be represented on a numerical scale. So, a significant difference from the control is designa- ted by 0, and an insignificant difference is designated by l on the graph. 51 l f, v 3 I z a l l . a Black 1 ' I Pepper 1 ‘ Aroma* ; 0 ) I I I 0 n 0 1 0 .1 J 0 0.28-0.35** Volatile Oil Loss (g/lOOg-dry product) *Black Pepper Aroma 1: Insignificant difference from the control by the sensory test. 0: Significant difference from the control by the sensory test **The critical volatile Oil loss range is 0.28 to 0.35g/100g-dry product in this study Figure 5. Black Pepper Aroma VS Volatile Oil Loss 52 Consideration of Moisture Effect The specifications for black pepper given by the F.D.A. and A.S.T.A. are in Table 2. Maximum moisture con- tent is specified because microbial spoilage readily oc- curs when the moisture exceeds twelve percent. This can be considered in the sorption isotherm. Figure 3 shows a pseudo sorption isotherm. We made an assumption that this pseudo isotherm includes the volatile oil loss and is par- allel to the actual sorption isotherm. Because the vola- tile oil loss is 2.259/lOOgoproduct and the actual initial moisture content is 8.509/100g-productpthe actual water sorption isotherm can be drawn. The unit of the pseudo isotherm was converted to g/lOOg-product and the volatile Oil loss (2.25g/100g°product) was added to this value. This is given in Figure 6 and is labeled "Revised Sorption Isotherms for Black Pepper." In the graph, when the equi- librium moisture content is lZg/lOOg-product, which is the limit specified by the F.D.A. and the A.S.T.A., the rela- tive humidity is about 80%. This means that the relative humidity in the package is allowed to be as high as 80%. In other words, no package is necessary for moisture pro- tection reasons if the relative humidity is less than 80%. In real life, black pepper is stored in a warehouse or in a supermarket where the relative humidity is usually less than 80%. Therefore, it can be concluded that the moisture effect for black pepper shelf life is not as important as volatile or non-volatile Oil. 53 g/lOOg-product Moisture Content (m) 12- 10- 8- 6- 4- 2- r I I l l 1 o 20 40 60 80 100% Relative Humidity (Hi) Figure 6. Revised Sorption Isotherms for Black Pepper 54 Error Analysis Several errors are involved in the experimental methods. They are considered in the following. Temperature (T) is the first factor to be consid- ered. The fluctuation of the temperature in the labora- tory was observed to be i 20F during the test. Even though this fluctuation is not large, its effect on the calcula- tion of the moisture weight change (AWm) should be anal— yzed. The temperature influences the following factors: the saturated partial pressure, the external relative hum- idity by the saturated salt solution method and the perme- ability constant of film. It may also influence the SlOpe of the sorption isotherm because our experimental result for the sorption isotherm (Figure 3) shows that the higher temperature has the steeper SlOpe. Considering all Of these factors, AWm in Equation (14) was recalculated. Table 15 shows the effect of temperature (77 : 20F, 100 : 20F) on the moisture weight change (AWm) of black pepper after seven days storage. In the table, it will be found that the maximum error is 0.064g/100g-dry product. The ratio of this error to AWm is 0.064 1.348 = 4°7% This should not be ignored. We can reduce this error by increasing the sensitivity. For example, if we use 1309 of black pepper for each sample instead of 1.39, the error can be reduced by a factor of 100. 55 Table 15. The Effect of Temperature (T) Fluctuations on the Moisture Weight Change (AWm) of Black Pepper AWm (g/100g'dry product) Film T 75°F 76°F 77°F 78°F 79°F M-24 AWm 0.548 0.569 0.595 0.621 0.642 Er* 0.047 0.026 -- 0.026 0.047 LDPE AWm 1.160 1.183 1.213 1.241 1.261 Er 0.053 0.030 -- 0.028 0.048 Film T 98°F 99°F 100°F 101°F 102°F M-24 AWm 1.064 1.074 1.055 1.095 1.106 Er 0.009 0.019 -- 0.040 0.051 LDPE AWm 1.412 1.401 1.348 1.375 1.363 Er 0.064 0.053 -- 0.027 0.015 *Er (Ergor at temperature T):O Difference between the values at 77 F and the values at T F or difference between the values at 100°F and the values at TOF. 56 The saturated salt solution method was used to maintain the constant relative humidity. According to Wink and Sears70 in 1950, the following factors are essential to Obtaining a stable relative humidity: the purity of the salt, the use of distilled water, a large solution sur- face area, a small headspace, and a stable temperature. These factors were well controlled in the experiment, but no attempt was made to measure the actual relative humid— ity inside the container. Assuming that the fluctuation of relative humidity was i 1% during the test, the moisture weight change of black pepper after 7 days storage can be calculated in Equation (14). The results are in Table 16. In Table 16, it will be found that the maximum error is 0.139g/lOOg dry product. The ratio of this error to AWm is 0.139 1.348 = 10.3% This value indicates that the external relative humidity is an important factor in the mathematical model. However, this value also can be reduced by increasing the mass of the pepper sample. The permeability constant (P) also includes several errors because it is based on a WVTR (water vapor trans- mission rate) measurement by the dish method. The fluctua- tion of temperature and relative humidity and the measure- ment of exposed film surface area are the possible factors giving rise to an uncertainty in P. The tolerance in P is estimated to be i 3% g-mil/cmZ/hr/Aatm. The results are 57 Table 16. The Effect of Relative Humidity (RH) Fluctua- tions on the Moisture Weight Change (AWm) of Black Pepper AWm (g/lOOg-dry product) 77°F 100°F Film RH 57.5% 58.5% 59.5% 52.7% 53.7% 54.7% M—24 AWm 0.554 0.595 0.636 0.947 1.055 1.164 Er* 0.041 -- 0.041 0.108 -- 0.109 LDPE AWm 1.129 1.213 1.296 1.209 1.348 1.487 Er* 0.084 -- 0.083 0.139 -- 0.139 *Er (Error at relative humidity RH): Difference be- tween the values at 58.5% and the values at RH% or differ— ence between the values at 53.7% and the values at RH%. in Table 17. The maximum error in AWm was found to be 0.020g/lOOg-dry product. This is a relatively small error. The film thickness is the next factor to be consid- ered. The film thickness varied by i 10% in the experi- ment. The error was analyzed assuming this range. The results are in Table 18. The maximum error in AWm was found to be 0.068g/100g-dry product. The other factors; the surface area, the volume of headspace, the slope of the sorption isotherm, and the weight of black pepper were also considered as error fac- tors. However, these errors are found to be negligible. A summary of the error AWm assuming maximum uncertainties for these minor contributing factors is found in Table 19. 58 Table 17. The Effect of Permeability Constnat (P) Differ- ence on the Moisture Weight Change (AWm) of Black Pepper AWm (g/lOOg-dry product) 77°F 100°F Film P* 1.314 1.364 1.414 2.61 2.71 2.81 M-24 AWm 0.575 0.595 0.621 1.037 1.055 1.072 Er 0.020 -- 0.017 0.018 -- 0.017 Film P 7.49 7.69 7.89 13.25 13.65 14.05 AWm 1.195 1.213 1.230 1.343 1.348 1.353 Er 0.018 -— 0.017 0.005 -- 0.005 -4 . 2 *P: (X 10 g-mil/cm /hr/Aatm) Table 18. The Effect of Film Thickness (2) Variation on the Moisture Weight Change (AWm) of Black Pepper AWm (g/100g-dry product) 77°F ) 100°F Film 2 0.45 mil 0.5 mil 0.55 mil 0.45 mil 0.5 mil 0.55 mil M-24 AWm 0.647 0.595 0.550 1.104 1.055 1.009 Er 0.052 -- 0.045 0.049 -- 0.046 Film 2 0.9 mil 1 mil 1.1 mil 0.9 mil 1 mil 1.1 mil LDPE AWm 1.281 1.213 1.151 1.361 1.348 1.334 Er 0.068 -- 0.062 0.013 -— 0.014 59 Table 19. Maximum Errors in AWm by the Effect of A, V, W, and b Estimated Range Max Error in AWm A 40 i 1 cm2 0.017 g/lOOg-dry product V 8 i 1 cc 0.001 w 1.30 i 0.05 g 0.020 b* (77°F) 0.0939 i 0.001 0.006 (100°F) 0.1096 + 0.001 0.011 *b: Slope of the sorption isotherm, g/lOOg-dry pro- duct/% RH. A: The surface area. V: The volume of headspace. W: The weight of dry product. From all of the above considerations, three important error factors were found. They were the temperature, the relative humidity, and the film thickness. The cumulative effect of these three important errors is estimated to be 0.167g/100g-dry product in the following calculation. ((0.064)2 + (0.139)2 + (0.068)2)l/2 = 0.167 Calculating the ratio of this maximum possible error to AWm in LDPE 0.167 at 77°F I‘2I3 = 13.8%, and at 100°F %L%%% = 12.4% These errors should not be ignored. However, these are the maximum possible errors. So, our results still can be 60 considered to be valid. These errors also can be decreased by increasing the mass of black pepper samples. CONCLUSION The critical volatile Oil loss was predicted by a combination of the mathematical-experimental model, and the sensory test. The result was confirmed by the chemi- cal analysis and the sensory test with expert panels. Both results agreed that the critical volatile oil loss was between 0.28 and 0.35g/100g-dry produCt. The sensory test results and the chemical analysis result indicated that the volatile Oil loss would be a reliable predictor of black pepper shelf life. It should be possible to develop a plastic package for black pepper by considering the critical volatile oil loss. Future Work When developing a plastic package for black pepper, the following problems must be considered. A. The stability of non-volatile oil should be con- sidered since this is another important factor for black pepper shelf life. B. It is a good idea to study the permeability of a plastic film against volatile oil. This will help the shelf life prediction in the future. 61 62 C. The sensitivity of the experiment should be im- proved by increasing the mass of black pepper. D. Black pepper has many varieties by its origin. Each variety might have critical volatile Oil loss differ- ent from others. E. The possibility of chemical reaction Should be considered. Volatile oil might interact with a plastic film and act as a plasticizer. This results in increasing I the permeability of the film. SUMMARY In order to achieve cost reduction of a black pepper package, a plastic pouch was proposed. The most essential requirement for the plastic package was to provide ade- quate shelf life. Three factors were considered in this study. These were volatile oil, non-volatile oil and mois— ture. Because aroma was the least stable factor in a black pepper storage test, the following hypothesis was made: the most critical factor for black pepper shelf life in a plastic package was its volatile oil loss. The crit- ical volatile Oil loss was predicted by a combination of mathematical-experimental model and a sensory test for black pepper aroma. This critical volatile oil loss was confirmed by a chemical analysis and a sensory test using an expert panel. These results indicated that volatile oil loss would be a reliable predictor of black pepper shelf life. In the sensory test with the expert panel, it was found that there was a significant difference in pepper heat between a stored sample and the control, but there was no significant difference in the total flavor between them. This meant that non-volatile oil was another im- portant factor to be considered in black pepper shelf 63 64 life, but it was more stable than volatile Oil. The moisture effect was also considered. Using the sorption isotherm of black pepper, it can be concluded that the factor of moisture was not as important as vola- tile or non—volatile Oil. By using the critical volatile Oil loss as a predic- tor, it should be possible to consider the shelf life of black pepper in plastic pouches. APPENDICES APPENDIX A TABLE FOR SIGNIFICANCE IN THE TRIANGLE TEST AND IN THE PAIRED TEST APPENDIX A TABLE FOR SIGNIFICANCE IN THE TRIANGLE TEST AND IN THE PAIRED TEST Table 20. Table for Significance in the Triangle Test* (P = 1/3) Minimum correct judgments to establish signifi- Number cant differentiation of Judges or Judgments Significance Significance Significance level 0.05 level 0.01 level 0.001 5 4 5 5 6 5 6 6 7 5 6 7 8 6 7 8 9 6 7 8 10 7 8 9 ll 7 8 10 12 8 9 10 13 8 9 11 14 9 10 ll 15 9 10 12 16 9 11 12 17 10 11 13 18 10 12 13 19 ll 12 14 20 ll 13 14 21 12 13 15 22 12 14 15 23 12 14 16 24 13 14 16 25 13 15 17 26 14 15 17 27 14 16 18 28 14 16 18 29 15 l7 19 30 15 17 19 31 16 17 20 32 16 18 20 33 16 18 21 34 17 19 21 35 l7 19 21 36 18 20 22 *Sensory Testing Method, "Encyclopedia of Industrial Chemical Analisis," 1973. 65 "YA-1 -“l v 66 Table 21. Table for Significance in the Paired Test* (P = 1/2) Minimum correct answers necessary to establish Number significant differentiation (one—tailed test) of judges or judgments Significant Significant Significant level 0.05 level 0.01 level 0.001 7 7 7 ’ 8 7 8 - 9 8 9 — 10 9 10 10 ll 9 10 ll 12 10 ll 12 13 10 12 l3 14 11 12 13 15 12 l3 l4 16 12 14 15 17 13 l4 16 18 13 15 l6 l9 14 15 17 20 15 16 18 21 15 17 18 22 16 17 19 23 16 18 20 24 17 19 20 25 l8 19 21 26 18 20 22 27 19 20 22 28 19 21 23 29 20 22 24 30 20 22 24 31 21 23 25 32 22 24 26 33 22 24 26 34 23 25 27 35 23 25 27 36 24 26 28 *Sensory Testing Method, "Encyclopedia of Industrial Chemical Analysis," 1973. APPENDIX B THE DERIVATION OF EQUATION (4) 67 APPENDIX B THE DERIVATION OF EQUATION (4) The Derivation of Equation (4)* M = M + M (3) 1 2 If W is the weight of the dry product in the pack- age and m is the moisture content, _ W Ml — m-Tb- (3.1) When the water in the product has reached equilibrium, m is given by the water isotherm, which is assumed to be a straight line. m = a + b’Hi(t) (3.2) From Equations (3.1) and (3.2) _ W . . Ml -—O—0- (a +le(t)) (3.3) Assuming the Ideal Gas Law is applicable to water vapor, Pi-v = n-R-T (3.4) where Pi is the pressure inside the package, V is the volume of the headspace, n is the number of water vapor molecules in the headspace, R is the gas constant, and T is the temperature. Since one mole of water vapor weighs 18g, and the water *Clifford, Wayne H., et al., 1977. 68 vapor pressure can be expressed in terms Of relative hum- idity, Equation (3.4) can be expressed as - , ,Hi(t), v M2 — 18 Ps 100 R,T (3.5) From Equations (3.3) and (3.5), . ' i M = 35—— (a + b-Hi(t)) + 18 —¥—-Ps-Hl(t) (4) 00 APPENDIX C THE DERIVATION FROM FICK'S LAW AND HENRY'S LAW TO EQUATION (5) 69 APPENDIX C THE DERIVATION FROM FICK'S LAW AND HENRY'S LAW TO EQUATION (5) The Derivation from Fick's Law and Henry's Law to Equation (5).* where but, where SO Fick's first law is F“ —_.§£ F - D 3x (5.1) D is the diffusion coefficient, 1 C is the concentration, L“ X is the space coordinate measured to the section, F is the flux (the rate of transfer per unit area of section). _: -—————' (C > C (5.2) 8x 2 2) C is concentration of side 1, l C is concentration of side 2, and 2 2 is the thickness of the material. F = D‘——————— (5.3) *Barrer, R. M., 1951. 70 From Henry's Law C = P-S (5.4) where P is the pressure, and S is the solubility coefficient. Plug (5.4) into(5.3). p - P F : DoSo____.__l 2 2 (505) where P1 is the pressure of side 1, P2 is the pressure of side 2, and P1 > P2. but, D-S = P (5.6) so P - P F = P 1 2 (5.7) 2 F is the rate of transfer per unit area of section. F = AU (5.8) where AM is the moisture weight change, At is the time period, and A is the unit area of section. Consider the limit of (%%) when At approaches zero. 71 1im (-°—M) - °M _ _ (5.9) At+0 At dt P1 and P2 can be expressed in terms of relative humidity. 13 = . (5.10) w u m (D m H- {I 2 100 (5.11) Here He > Hi(t) From Equations (5.7), (5.8), (5.9), (5.10) and (5.11), 99 = P A 3§—.(He - Hi(t)) (5) dt 2 100 APPENDIX D THE DERIVATION OF EQUATION (7) +57 .1. ' 5-.\"'“« 72 APPENDIX D THE DERIVATION OF EQUATION (7) The Derivation of Equation (7).* — A Ps . _ d_ W . . P P —65(He - Hl(t)) — dt(150(a + b H1(t)) v Hi(t) + 18R T P 100 ) §.§.__§ dHi(t) _ 1 100 _ . 100 100R T Let p.§. PE _ 2 100 _ P-A-Ps = J bw + 18Ps-v ‘ 2(18Ps-V/R-T + b'W) 00 100R'T Integrate Equation (6.1) dHi(t) He - Hi(t) f = det Let He - Hi(t) = K Differentiate (6.3) -dHi(t) = dK From Equations (6.2),(6.3) and (6.4), dK ’ f_K = fJ‘dt *Manathanya, Vallop, 1976 (6) (6.1) (8) (6.2) (6.3) (6.4) (6.5) 73 1n K + constant (1) = -J-t K = constant (2)-e- J°t He - Hi(t) = constant (2)-e’ when t = 0 Constant (2) = He - Hi(O) From Equation (6.8) and (6.9), Hi(t) He - (He - Hi(0))°e- Jo J. t t (6.6) (6.7) (6.8) (6.9) (7) APPENDIX E SENSORY TEST FOR PEPPER FLAVOR: COOKING PROCEDURE FOR THE MEDIA AND SERVING PROCEDURE 74 APPENDIX E SENSORY TEST FOR PEPPER FLAVOR: COOKING PROCEDURE FOR THE MEDIA AND SERVING PROCEDURE The potato soup media consisted of the following in- gredients. 200g Chicken broth 2009 Water 3009 Milk 300g Cooked White Potatoes The soup was blended for one minute on the stir Speed and for one minute on the mix speed of a blender. The black pepper was diluted in the soup to 0.125% and al— lowed to stand for 20 minutes. Panelists were served 20 m1 of each sample in coded medicine cups. Sample order of presentation was rotated to avoid bias and red lights masked color differences. APPENDIX F VOLATILE OIL CONTENT OF BLACK PEPPER BY STEAM DISTILLATION .‘- 75 APPENDIX F VOLATILE OIL CONTENT OF BLACK PEPPER BY STEAM DISTILLATION Reagents and Apparatus Flask - 1 liter, round-bottom, short neck Electric Heating Mantle Oil Traps - 5.0 ml distilling trap, Clevenger type, boiling flask, and finger condenser Condenser - Drip—tip, 400 mm long Pipet - 5 m1 Antifoam Boiling Chips Salt-crystals Detergent - 3% V/V aqueous solution Wire - copper Procedure 1. Grind sample. 2. Weigh 50.0 g of the sample. 3. Transfer the sample quantitatively to the dis- tilling flask. 4. Add 500 ml of water, two drops antifoam boiling chips and thoroughly mix the contents. 5. Clean the dilution trap immediately before use by filling with boiling 3% aqueous solution Of detergent for 10 minutes, then rinse well but do not dry. ' Emu—u 76 6. Connect oil trap to the flask and add water to the graduated portion of the trap. 7. Connect to condenser and distill overnight. 8. Cool and determine volume (ml) of Oil collected. Calculation Corrected Volume of 011 (ml) x 100 Sample Weight (g) = % V/W Volatile Oil APPENDIX G NON-VOLATILE OIL OF BLACK PEPPER DETERMINED BY SOLVENT EXTRACTION 77 APPENDIX G NON-VOLATILE OIL OF BLACK PEPPER DETERMINED BY SOLVENT EXTRACTION Reagents and Apparatus Methylene Chloride — A.C.S. grade Extractor - standard continuous extraction apparatus Extraction Thimbles - paper Oven - 1100C circulating air type Aluminum Dish - 70 x 10 mm Procedure 1. Weigh approximately 2.000 g Of sample in a paper extraction thimble of medium porosity. 2. Place the thimble in the extraction apparatus and extract 20 hours with Methylene Chloride. 3. Transfer the extract, using several solvent washes to a tared aluminum dish and evaporate the solvent on a steam bath in a forced draft hood. 4. Place the dish in a drying oven at 1100C : 2°C and weigh hourly until the difference in con- secutive weighings is not more than 1 mg. Calculation Weight of Residue in Dish (9) x 100 Sample Weight (g) = % Non-Volatile Extract Report as percent Non-Volatile Methylene Chloride Extract. REFERENCES 10. REFERENCES American Society for Testing Materials. Standard Method of Test for Water Vapor Transmission in Sheet Form, E96-66 (Reapproved 1972). American Spice Trade Association, Official Analytical Methods of the American Spice Trade Association, 1960. Amerine, Maynard A., Rose Marie Pangborn, and Edward B. Roessler. "Principles of Sensory Evaluation of Food." New York: Academic Press, 1965. Barrer, R. M. "Diffusion In and Through Solids, Cam- bridge Press, 1951. Boguet, Reimaldo, Jorge Chirife, and Hector A. Iglesias. 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