m . 5W A ’ mg”: 6, 1': ram .x f "WJ' ‘3 3 ~ 3;; $523. w r94"... -. «.2 ”Iii-fin 22%; 3,; ‘u. 1. 4-414 ”firm "trim-32:41??? “ .gh:«:i%*‘¢w . , i . - ’“"“,Awl?§% “ ‘ ~. . '.’ ‘ ~' " ‘W . .2 1» Hams; L ,u. ‘ - 3 "up; a}, - - .:.~ ,2 u‘ _-. 7,39% . 0‘, ~. .17 , s “ “11:... a» “ 36“ s we , Wi‘"i%£l%& ‘ ‘ - " -' ‘L " '3 .“ ; .~ 3%»; “31.3% "x 135~¢~$fimm 1%; 335333 ._ ~1 " '5' 3‘ vifit‘ct‘féli‘fi': #33“. 40x53!" W .4 J.-'a‘;«.;‘,,.. E, --v‘~'5§-:§Z£\m-. "‘ 5'43““. v'~ h! ,7 1. Iv ’ 1. ¢ mr UBRARIES lll‘llllll MlCHlGAN S ATE UN \\\IERS \llllll l llll \\\\\l i 3 1293 01 l This is to certify that the thesis entitled RATE OF LIPID OXIDATION AT VARYING INITIAL OXYGEN CONCENTRATIONS USING OXYGEN ABSORBING SACHETS IN THE PACKAGES presented by Dena Briggs Thomas has been accepted towards fulfillment of the requirements for M . S . degree in Packaging Major professor Date I 0-7639 MSU is an Affirmative Action/Equal Opportunity Institution LIBRARY Mlchlgan State Unlverslty PLACE N RETURN BOXtorommmbchockMflom yournoond. TO AVOID FINES Mum on or Mon dd. duo. ' DATE DUE4 DATE DUE DATE DUE ,' I . II I l MSU In An Alfimntlvo Maul Oppommlty Intuition W MT RATE OF LIPID OXIDATION AT VARYING INITIAL OXYGEN CONCENTRATIONS USING OXYGEN ABSORBING SACHETS IN THE PACKAGES BY Dena Briggs Thomas A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE School of Packaging 1994 ABSTRACT RATE OF LIPID OXIDATION AT VARYING INITIAL OXYGEN CONCENTRATIONS USING OXYGEN ABSORBING SACHETS IN THE PACKAGES BY Dena Briggs Thomas This study was performed to determine the effect of varying initial oxygen concentrations and the use of oxygen absorbers on the shelf life of potato chips packaged in metallized polyester and metallized polypropylene. Potato chips were stored for 22 weeks. Changes in headspace oxygen concentration, moisture content, and hexanal concentration were measured. The hexanal and sensory data showed that chips in metallized polypropylene at 10% initial oxygen concentration with an absorber were less rancid than chips at lower oxygen concentrations without absorbers and less rancid than chips at 2% initial oxygen concentration with absorbers. The hexanal data also showed that chips in metallized polyester without absorbers produced significantly more hexanal at an initial oxygen concentration of 2% than at an initial oxygen concentration of 0.2%. ACKNOWLEDGMENTS Dr. Theron Downes: For his guidance, patience, understanding, and enthusiasm as my major advisor. Dr. Jack Giacin: For sharing his technical expertise and wisdom, and for always being available while serving on my committee. Dr. William C. Haines: For his jovial spirit and for serving on my committee. Dr. Hugh Lockhart: For keeping me employed on interesting and challenging projects during the course of my study at the School of Packaging, and for his advice and help with my thesis work. Dr. Jerry Cash: For his advice and help with potato chip processing. Dr. Ahmad Shirazi: For use of the Food Science processing pilot plant. Don Abbott: For being a bright spot during difficult times. My family, especially my parents: For their encouragement, faith, and continuous moral support. My husband, Jon Thomas: For his patience and devotion. iii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . NOMENCLATURE. . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . LITERATURE REVIEW . . . . . . . . . . Mechanism of Lipid Oxidation . . Factors Influencing the Rate of O i Light . . . . . . . . . . . Transition Metals . . . . . Temperature . . . . . . . . Water Activity . . . . . Monolayer Moisture Cont n Oxygen Availability . . . . Antioxidants . . . Methods of Quantifying Oxidation Peroxide Value (PV) . . . . ooofloooogoo X e Thiobarbituric Acid Reactive Substance (TEARS) . . . . . . . Hexanal . . . . . . . . . . Oxygen Scavengers (Absorbers) . Metal-complex Scavengers . at 00000000000 Non-metal Chemical-complex Scavengers Photosensitive Dye Scavengers . Enzyme Scavenger Systems . . . Synthetic "heme" Scavenger . . METHODS . . . . . . . . . . . Potato Chip Manufacture . . Initial Moisture Content . . Sorption Isotherm . . . . . Packaging . . . . . . . . . Water Vapor Transmission Rate Chip Weights . . . . . . . . Volume Measurement . . . . . . Meadspace Oxygen Concentration Storage . . . . . . . Hexanal Quantification . . . . Apparatus for Trapping of ”00.00.0000. p. Hooooooooooo D! <. D O I O O O O O O O 0 iv [—50 o o o o o o o o o o (D vii xi xii H \ommmmbhuu RESULTS AND DISCUSSION . . . SUMMARY AND CONCLUSIONS . . . . . APPENDICIES O O O I O O O O O O O O O O O O I O Trapping of Volatiles . . . . . . . . . . . Extraction and Concentration Procedure . . . Percent Recovery of Hexanal From Tenax and Concentration Technique . . . . . . Gas Chromatography . . . . . . . . . . . . . Hexanal Calibration Curve Development Procedure . . . . . . . . . . . . . . . Product Model . . . . . Storage Environment . . Initial Moisture Content Equilibrium Sorption Isotherm . . . . . Using the Brunauer, Emmett, and Teller (BET) Monolayer Mathematical Model to Predict Product Moisture Content at Specific Water Activities . . . . . . . . . . . . . . Brunauer, Emmett, and Teller Monolayer Value Water Vapor Transmission Rate and Permeability . Chip Weights . . . . . . . . . . . . . . . . . Volume Measurement . . . . . . . . . . . . . . Oxygen Permeability . . . . . . . . . . . . . Data Collection and Analysis of Headspace Sampling . . . . . . . . . . . . . Headspace Sampling of Oxygen . . . . Collection of Hexanal from Potato Chips . Hexanal Data and Quantification . . . . . Percent Recovery of Hexanal from Tenax-GR Statistical Difference Between Groups According to Hexanal Data . . . Sensory Evaluation . . . . . . . . . . . . Discussion of Hexanal and Sensory Results. Error Analysis . . . . . . . . . . . . . . BET Monolayer Moisture Content Headspace Oxygen Concentration Applicability of Results . . . A. Gas Chromatograph Hexanal Calibration Data . . . . . . . . . . . B. Chip Initial Moisture Content Data C. Sorption Isotherm Data . . . . . . D. WVTR Data, Package Weights . . . . E. WVTR Data, Package Weight Gains . . F. Weights of Potato Chips . . . . . . G. Weight Gains of Potato Chips . . . H. Initial and Final Volumes of Potato Packages . . . . . . . . . . . I. Headspace Oxygen Concentration Over Time . . . . . . . . . . . . . . . . . . 000000000 :1 oHoooooooo '0 V 29 29 31 31 32 34 34 34 35 35 38 39 41 43 47 47 47 47 53 53 55 55 58 59 60 62 62 63 63 65 65 69 7O 71 73 76 84 92 97 J. Potato Chip Hexanal Data . . . . . . . . . . 99 K. Percent Recovery Data & Calculations . . . . 108 LI ST 0F REFERENCES 0 O O O O O O O O O O O O O O O O O 109 1. 2. 10. 11. 12. 13. 14. 15. 16. 17. LIST OF TABLES Packaging Characteristics of Different Groups. Equilibrium Moisture Contents at Each Water Activity . . . . . . . . . . . . BET Model Expected Values (X.) versus Actual Equilibrium Product Moisture Content Values. . B.E.T. Regression Plot Values for the Sorption Isotherm for Determining Monolayer Value . . . Water Vapor Transmission Rate Data . . . . . . Hexanal Concentration in Potato Chips over T ime ( ppm ) O O O I O O O O O I O O O I O Hexanal Data for the First Calibration Curve . Hexanal Data for the Second Calibration Curve Chip Initial Moisture Content Data . . . . . . Sorption Isotherm Data . . . . . . . . . . . . Metallized Polyester Package Weights . . . . . Metallized Polypropylene Package Weights . . . Metallized Polyester Package Weight Gains. . . Metallized Polypropylene Package Weight Gains. Average and Net Package Weight Gains . . . . . Weights (g) of Potato Chips Packaged in Metallized Polyester at 0% 02. . . . . . . . . Weights (g) of Potato Chips Packaged in Metallized Polyester at 0% 02 with an Absorber 22 36 39 41 43 54 65 67 69 7O 71 72 73 74 75 76 77 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. Weights (g) of Potato Chips Packaged in Metallized Polyester at 2% 02. . . . . . . . . Weights (g) of Potato Chips Packaged in Metallized Polyester at 0% 02 with an Absorber Weights (g) of Potato Chips Packaged in Metallized Polypropylene at 2% 02. . . . . . Weights (g) of Potato Chips Packaged in Metallized Polypropylene at 2% 02 With an Absorber O O I O O O O O O O O O O O Weights (g) of Potato Chips Packaged in Metallized Polypropylene at 10% 02 . . . . . Weights (g) of Potato Chips Packaged in Metallized Polypropylene at 10% 02 with an Absorber . . . . . . . . . . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polyester at 0% 02. . . . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polyester at 0% 02 with an Absorber Weight Gains (g) of Potato Chips Packaged in Metallized Polyester at 2% 02. . . . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polyester at 0% 02 with an Absorber Weight Gains (g) of Potato Chips Packaged in Metallized Polypropylene at 2% 02 . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polypropylene at 2% 02 with an Absorber . . . . . . . . . . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polypropylene at 10% 02 . . . . . Weight Gains (g) of Potato Chips Packaged in Metallized Polypropylene at 10% 02 with an Absorber O O D O O O I O O O O O O 0 Initial and Final Volumes of Potato Chip Packages of Metallized Polyester Inflated with Nitrogen . Initial and Final Volumes of Potato Chip Packages of Metallized Polyester Inflated with Nitrogen and Packaged with Oxygen Absorbers . . . . . viii 78 79 80 81 82 83 84 85 86 87 88 89 9O 91 92 92 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. Initial and Final Volumes of Potato Chip Packages of Metallized Polyester Inflated with 2% Oxygen/98% Nitrogen . . . . . . . . . . . . . . Initial and Final Volumes of Potato Chip Packages of Metallized Polyester Inflated with 2% Oxygen/98% Nitrogen and Packaged with Oxygen Absorbers . . . . . . . . . . . . . . . . . Initial and Final Volumes of Potato Chip Packages of Metallized Polypropylene Inflated with 2% Oxygen/98% Nitrogen . . . . . . . . . . . . . . Initial and Final Volumes of Potato Chip Packages of Metallized Polypropylene Inflated with 2% Oxygen/98% Nitrogen and Packaged with Oxygen Absorbers . . . . . . . . . . . . . . . . . Initial and Final Volumes of Potato Chip Packages of Metallized Polypropylene Inflated with 10% Oxygen/90% Nitrogen . . . . . . . . . . . . . . . Initial and Final Volumes of Potato Chip Packages of Metallized Polypropylene Inflated with 10% Oxygen/98% Nitrogen and Packaged with Oxygen Absorbers . . . . . . . . . . . . . . . . . Average Headspace Oxygen Concentrations (%) of Metallized Polyester Packages Over Time . . . . . Average Headspace Oxygen Concentrations (%) of Metallized Polypropylene Packages Over Time . . . Hexanal Data for Fresh Chips . . . . . . . . . . . Hexanal Data for Chips in Metallized Polyester; 0% Initial 02; Without an Absorber . . . . . . . Hexanal Data for Chips in Metallized Polyester; 0% Initial 02; With a 100cc Capacity Absorber . . Hexanal Data for Chips in Metallized Polyester; 2% Initial 02; Without an Absorber . . . . . . . . Hexanal Data for Chips in Metallized Polyester; 2% Initial 02; With a 200cc Capacity Absorber . . Hexanal Data for Chips in Metallized Polypropylene; ix 93 93 94 94 95 96 97 98 99 100 101 102 103 104 48. 49. 50. 51. hexanal Data for Chips in Metallized Polypropylene; 2% Initial 02; With a 200cc Capacity Absorber . . . . . . . . . . Hexanal Data for Chips in Metallized Polypropylene; 10% Initial 02; Without an Absorber . . . . . . . . . Hexanal Data for Chips in Metallized Polypropylene; 10% Initial 02; With a 400cc Capapcity Absorber . . . . . . . . . . Percent Recovery Data & Calculations . 105 106 107 108 10. 11. 12. 13. 14. LIST OF FIGURES Effect of Water Activity on the Rate of Chemical Reactions in Foods . . . . . . . . . . . . . . . Storage Arrangement of Potato Chip Packages . . Apparatus for Trapping of Volatiles . . . . . . Sorption Isotherm . . . . . . . . . . . . . . . Brunauer, Emmet, and Teller Plot for Determining Moisture Weight Gain Over Time of Packaging materials 0 O O O O O O O O O I O O O O O O O 0 Chip Moisture Content Over Time . . . . . . . . Chip Moisture Content Over Time; Actual vs. Predicted Values . . . . . . . . . . Headspace [02] Over Time of Metallized Polyester Packages Initially Flushed with Nitrogen . . . . Headspace [O ] Over Time of Metallized Polyester Packages IniIially Flushed with 2% 02; 98% N2 . Headspace [0%] Over Time of Metallized Polypropylene Packages Ini ially Flushed with 2% Oz; 98% N2 . Headspace [02] Over Time of Metallized Polypropylene Packages Initially Flushed with 10% 02; 90% N2 . First Hexanal Calibration Curve . . . . . . . . Second Hexanal Calibration Curve . . . . . . . . xi 26 28 37 40 42 45 46 49 50 51 52 66 68 AU BET C, C °C CC CCS NOMENCLATURE water activity Area Response Units Brunauer, Emmett, and Teller constants degrees Celcius cubic centimeters Calibration Curve slope equilibrium moisture content equilibrium relative humidity degrees Farenheit gram gas chromatograph concentration of hexanal in product sample(ng/g) initial moisture content a free radical any unsaturated fatty acid the peroxyl radical a lipid hydroperoxide moisture content (dry basis) monolayer value milliliter millimeter microliter singlet oxygen hydroxyl radical product weight partial pressure of water above the sample vapor pressure of pure water xii PET PP ppb Pf Pi ppm PV R1: R2 water vapor permeability of each package polyester polypropylene parts per billion final product weight initial product weight parts per million peroxide value relative humidity of the external and internal package environments relative humidity saturation vapor pressure standard temperature and pressure thiobarbituric acid thiobarbituric acid reactive substances Volume of injection Total sample volume weight change weight of dry product initial weight dried weight water vapor transmission rate water vapor transmission rate for each package xiii IEIEQDEQIIQH Lipid oxidation is a major limiting factor in the shelf-life of potato chips. The major products of lipid oxidation are hydroperoxides, which are colorless, tasteless, and odorless. Hydroperoxides, however, break down to low molecular weight compounds which impart flavors and odors to food products that are associated with rancidity. The secondary products of oxidation are free radicals, peroxides, epoxides, aldehydes, ketones, cyclic monomers, dimers, and polycyclic aromatic hydrocarbons; many of which are toxic (Bidlack et a1. 1973). Several factors can influence the rate of lipid oxidation. Jean (1983) reports that factors such as light, relative humidity, temperature, type of frying oil used and availability of oxygen affect the production of lipid oxidation products. Quast and Karel (1971) report that lipid oxidation is likely the most common mechanism of oxygen uptake in dried foods such as potato chips. For fried foods, the extent of oxidation of the frying oil also contributes to the product's oxidation. Over the years, different products of oxidation have been measured as indices of the extent of lipid oxidation. Peroxide value, thiobarbituric acid reactive substances (TBARS), and hexanal are three that are commonly used. Oxygen absorbers have long been used to reduce oxygen in the headspace of packages to prolong shelf-life without adding preservatives. Patents for oxygen absorbers have been granted as early as 1938. There are several different types of oxygen absorbers currently being developed. The most common oxygen scavenger on the market today is an iron complex which oxidizes to rust. These absorbers can be adjusted with humidity factors that will make them usable with a variety of products with low to intermediate water activities. That is the type that will be used in this study. The objectives of this study were to: 1. Determine an initial headspace oxygen concentration above which the rate of lipid oxidation proceeds independent of the oxygen concentration. 2. Determine the extension in shelf-life obtained by using an oxygen absorbing sachet in packages with initial oxygen concentrations of 0%, 2%, and 10%. 3. Determine how using metallized polyester and metallized polypropylene with and without absorbers affects the rate of lipid oxidation. Ia2haniaa_21_nini§_gzi§atien The mechanism of oxidation is well documented (Gutteridge and Halliwell, 1990; Nawar, 1985). Lipids oxidize by a free-radical chain process. This process has 3 steps: 1)Initiation, free-radical formation; 2)Propagation, free-radical chain reactions; and 3)Termination, formation of non—radicals. Initiation: LH + 02 --> L- + -OH Propagation: L- + 02 --> L00- L00- + LH --> LOOH + L-; etc. Termination: L- + L- --> LL or L- + LOOI --> LOOL or Loo. + Loo. --> LOOL + 02 LH is any unsaturated fatty acid, L- is a free radical formed by removing hydrogen from a carbon next to a double bond, LOO: is the peroxyl radical formed, and LOOK is a lipid hydroperoxide, the major primary lipid oxidation byproduct. In linoleic acid, a hydrogen is removed from the doubly allylic methylene on carbon-11 to create a delocalized pentadienyl radical. Oxygen addition at carbons-9 and -13 produces conjugated 9- and 13- hydroperoxide isomers (Frankel, 1984). Hydroperoxides readily decompose into the many secondary byproducts of oxidation. Nawar (1985) points out that the initiation reaction in this process has a high activation energy making the 3 reaction unlikely without a catalyst. Some catalysts of the initiation step are thought to be transition metals, light, decomposing hydroperoxides, and singlet oxygen (102). Singlet oxygen is also believed responsible for photosensitized oxidation. Singlet oxygen is electrophilic enough to react directly with a double carbon bond, whereas stable (triple state) oxygen is not (Nawar, 1985). When linoleate is photosensitized by singlet oxygen, four hydroperoxide isomers are formed: conjugated 9- and 13- diene and unconjugated 10- and 12-diene hydroperoxides (Frankel, 1984). WWW: Light, transition metals, temperature, water activity, oxygen availability, antioxidants, and the type and condition of oil all can influence the rate of lipid oxidation in fried foods. Light Light has been known to contribute to oxygen uptake and subsequently oxidation for many years. Several have studied the effects of light on lipid oxidation. Quast and Karel (1972) demonstrated that artificial room light or sunlight will increase oxygen uptake by potato chips, and as water activity increases, this effect becomes more significant. A study performed by Columbus Instruments International Corporation showed that potato chips exposed to a 30 watt lamp light at 43°C consumed oxygen at a rate twenty times greater than potato chips stored in the dark at 22°C (Columbus Instruments International Corporation, 1993). Jeon and Bassette (1984) monitored n-hexanal production in fluorescent light-exposed potato chips and potato chips stored in the dark. They found that light-exposed potato chips produced moderately higher amounts of n-hexanal than control chips over the first 60 hours of the study, and rapid production of n-hexanal occurred in light-exposed potato chips after 60 hours. Fluorescent lighting is commonly used in grocery stores and emits light in wave lengths between 350 and 500 nanometers. Kail (1984) reports that only blue-printed and metallized structures adequately protect snack foods from acceleration of oxidation by light. Transition Metal: Transition metals, such as copper and iron, can shorten the induction period and increase oxidation rate. Trace amounts of heavy metals are found in most edible oils. They are picked up from the soil during plant growth or from equipment during processing (Nawar, 1985). Because these transition metals can exist in two or more valency states, they have oxidation-reduction potential and are pro- oxidants. They can act as pro-oxidants in accelerating hydroperoxide decomposition, attacking an unoxidized substrate to remove a hydrogen and form a free radical, or activating oxygen molecules to the singlet oxygen state. Temperature It is well known that increasing temperature increases molecular movement. Thus, logic dictates that a high- temperature storage environment will have oxygen molecules that move quickly and have increased affinity for free radicals in the lipid oxidation process, increasing the oxidation rate. However, Quast and Karel (1972) state that temperature has a weak effect on the rate of oxidation in potato chips, and therefore if accelerated testing is to be done, relatively high temperatures must be used. Berends (1993) found that as oxygen concentration was held constant, greater amounts of hexanal were produced as the temperature increased from 23°C to 40°C to 66°C. water Activity Perishability of foods is strongly related to moisture content. However, different foods with the same moisture content vary greatly in perishability. The difference can be attributed, in part, to how tightly water binds with nonaqueous constituents. Tightly bound water will not support degradative activities, and different foods will allow more or less water to be tightly bound, thereby having different moisture contents at the same level of water activity (Fennema, 1985). Water activity (aw) is defined as the partial pressure of water above the sample (p) divided by the vapor pressure of pure water (p0) at the same defined temperature. This is also equal to the equilibrium relative humidity (ERR) of a food at a given moisture content divided by 100. Water activity is related to moisture content through a sorption isotherm. The rate of lipid oxidation is greatly affected by a food's water activity. Dried foods and high moisture foods will oxidize at a faster rate than intermediate moisture foods. Oxidation proceeds rapidly at water activities below 0.1, but as water activity increases, oxidation rate decreases. It is believed that this protective effect of water is due to hydrogen bonding of hydroperoxides, deactivation of transition metals, and water interfering with free radicals (Nawar, 1985; Labuza et al., 1970). At water activities between 0.55 and 0.85 the rate of oxidation increases. This is likely due to increased mobilization of catalysts. Several studies of model systems confirmed this and suggested that the high water content also exposed new catalysts sites by swelling the polymeric matrices (Heidelbaugh and Karel, 1970; Heidelbaugh et al., 1971; Labuza et al., 1970; Labuza et al., 1971; Karel and Yong, 1981). At very high water activities catalysts are diluted, thus reducing the oxidation rate. A generalized view of the effect of water activity on the chemical reactions in food systems is described by the "stability map" given in Figure 1, adopted from Labuza (1971). lNBiNOO BUOISIOW RELATIVE REACTION RATE WATER ACTIVITY Figure 1: Effect of Water Activity on the Rate of Chemical Reactions in Foods Monolayer Moisture Content Minimum reaction rates for degradative processes including oxidation occur at what is called the monolayer water content. Below this monolayer water content the rate of oxidation increases. Therefore, the monolayer water content is the water content which provides the maximum stability of a dried food. The monolayer water content of a food can be computed using the sorption isotherm data and the Brunauer, Emmett, and Teller (BET) equation (Brunauer et al. 1938). The BET equation is aw/[m(1-aw)] = 1/m1c + [(C-1)/(m1c)](aw) (1) where aw equals water activity, m stands for moisture content (dry basis), m1 is the monolayer value, and C and c are constants. When aw/[m(1-aw)] is plotted against aw for water activities below 0.4, a straight line is generated. From this straight line the monolayer value, m1, is found to be 1/(y-intercept + slope). This monolayer water content value will correspond to a specific water activity in the product's sorption isotherm. Oxygen Availability The most common mechanism of oxygen uptake in dried foods is probably lipid oxidation as described by Quast and Karel (1971) when studying the rate of oxygen uptake by potato chips fried in sunflower oil with no antioxidants added. They found that in the induction period of oxidation the rate of oxygen uptake is only about one-hundredth of that of chips in the post-induction phase. In 1972, Quast and Karel used 20 g samples of potato chips and found that chips absorb approximately 1200 ul OstP/g during the induction period. The length of the induction period would vary depending on water activity, light, temperature, and frying oil, but the quantity of oxygen absorbed during the induction period appeared independent of these factors. The amount of oxygen absorbed during the induction period was 10 enough for the chips to become significantly rancid from a flavor standpoint. They also found that oxygen diffusion into potato chips is only likely to be an oxidation rate limiting factor at partial pressures below 0.05 atm except when the relative humidity is also very low. Antioxidants Antioxidants are substances that can retard the rate of oxidation or lengthen the induction period. Since food processing oils are exposed to many oxidation catalysts throughout processing, antioxidants are commonly used in these oils specifically for this purpose. The most common action of an antioxidant is accepting free radicals to slow the propagation of oxidation. Cavaletto and Yamamoto (1971) found that adding antioxidants to the frying oil used in roasting macadamia nuts increased the stability of the kernels. WW Over the years peroxide value (PV), thiobarbituric acid reactive substances (TBARS), and hexanal have been used to measure the level of oxidative rancidity in food products. Peroxide value (PV) There are numerous analytical procedures for measuring PV. The majority are idometric and they are useful for bulk 11 lipids and applicable to all normal fats and oils. However, the idometric measurement is highly empirical and any variation in procedure may result in a variation in results (Gray 1991). Other errors that are associated with the idometric measurement are possible adsorption of iodine at unsaturated bonds of fatty acids and liberation of iodine from potassium iodide by oxygen present in the solution to be titrated. Since peroxides are the primary byproduct of lipid oxidation, they are a good measure of oxidation in its initial stage. However, peroxides decompose to secondary oxidation byproducts, making them a poor choice for measurement of oxidation over long periods of time. Thiobarbituric Acid Reactive Substances (TBARS) The TBA test was originally meant to measure the level of malonaldehyde (a toxic substance) in a product. However, more substances than just malonaldehyde react with 2- thiobarbituric acid (TBA). Therefore, TBARS is a more accurate description of the measured quantities. Problems associated with TBARS values include the fact that some non- lipids react with TBA and that TBARS can be produced during the testing procedure (Gray, 1991). The assay numbers reported as milligrams of malonaldehyde equivalents per kilogram of sample are also operator dependent and method dependent (Gray and Monahan, 1992). 12 Hexanal A third method for measuring rancidity is to measure a volatile product of lipid peroxide decomposition using a gas chromatograph (GC). Melton (1983) concluded that direct quantification of peroxide decomposition products by GC may be more accurate than the TBA test for measuring oxidation. Hexanal is one of the major secondary products of linoleic acid oxidation (Frankel et al., 1981), and the predominant precursor of n-hexanal is free linoleic acid (Matoba et al., 1985). Hexanal was found to comprise the largest proportion of steam-volatile compounds formed by autoxidized potato granules (Buttery, 1961). It was four times more concentrated than any other component and ten times more concentrated than most other compounds. In 1965, it was shown that hexanal was the saturated aldehyde that increased the most during storage of potato chips (Mookherjee et al., 1965) and the flavor produced over the storage period was described as "stale," not rancid. One concern with measuring hexanal as an indication of oxidation is how well it correlates with sensory data. In 1971, Fuller et al. found sensory evaluation to be more sensitive to oxidation than hexanal measurement. However, in 1981 Tang used a Tenax trapping system with potato chips and found good correlation between diminishing sensory hedonic scores over time and increasing n-hexanal concentrations over time. Fritsch and Gale (1977) found 13 that rancid odors in low fat foods corresponded to hexanal concentrations of five to ten parts per million (ppm). WM). For many years, people have been trying to extend shelf-life of food products by removing oxygen from the headspace of packages. As early as 1938 a patent was granted in Finland for keeping food in a closed container with zinc dust, iron powder and some other compounds. Oxygen scavengers allow for extended shelf-life without the use of preservatives. Today oxygen scavengers used in packages can be divided into the five major categories of metal-complex scavengers, non-metal chemical-complex scavengers, photo-sensitive dye scavengers, enzyme scavengers, and synthetic heme-complex scavengers. Metal-complex Scavengers Iron is the main active component in most metal-complex oxygen scavengers. Iron is relatively inexpensive, safe, has FDA clearance, has a manipulatable reaction rate with oxygen, and has a much greater affinity for oxygen than most food products (Idol and wagner). Sulfur produces by products which are difficult to control and impart off- flavors or odors. Aluminum forms a protective skin of oxidized metal. Palladium and platinum are very expensive (Idol and Wagner). The common iron-complexes are generally 14 contained in sachets which are dropped into the food package. "Ageless" is the name of the oxygen scavenger distributed by Mitsubishi which controls about 70% of the market share (Sacharow, 1991). These sachets are used in Japan and Europe in many products such as bakery goods, precooked pasta, cured or smoked meats, dried foods, nuts, coffee, cheese, and chocolates (Labuza and Breene, 1989). The amount of iron needed in a sachet is dependent upon the initial oxygen in the headspace, the amount of dissolved oxygen in the food, and the package permeation rate. In general, 1 gram of iron can react with 0.0136 moles of oxygen (STP) which is equal to approximately 300 cc. The chemical reaction is 4 Fe + 3 02 --> 2 Fe203. Headspace oxygen concentrations have been maintained at less than 0.01% using metal-complex oxygen scavengers. The rate of oxygen absorption is dependent on oxygen concentration and humidity. Many different complexes have been designed to serve specific needs of food products. Multiform Desiccants, Inc. has specifically designed absorbers for use in moist foods (aw>0.65), dry foods (0.0 DYE(excited state) DYE(excited state) + OXYGEN --> DYE + OXYGEN(excited state) OXYGEN(excited state) + ACCEPTOR --> ACCEPTOR OXIDE 0XYGEN(excited state) --> OXYGEN Rubber has been studied, not only as a matrix for holding acceptors, but also as a highly concentrated acceptor in itself. If acceptors approved for food contact can be developed, the advantages of this system would be 17 that no sachets would need to be added to the packages and the scavenger system would not become active prior to use as long as they are stored in the dark. lnsyse Scavenger Systems Glucose oxidase is a known oxidoreductase, transferring two hydrogens from the -CHOH group of glucose to oxygen forming glucono-delta-lactone and hydrogen peroxide. One mole of glucose reacts with one mole of oxygen. However, catalase is a normal contaminant in glucose oxidase and it decreases the effectiveness of glucose oxidase by half. Pure glucose oxidase is very expensive. Glucose oxidase (with catalase) has GRAS (generally regarded as safe) status and can be added to food products such as beer or wine to eliminate dissolved oxygen in the product (Labuza and Breene, 1989).. However, the oxidation reaction forms off- flavor by-products which are detectable in beer (Zenner and Salame, 1989). Scott and Hammer (1961) suggested using the glucose oxidase in sachets in dried foods with a humidity factor within the sachet to drive the reaction. They also have a patent for spreading the enzyme in a fine particle matrix throughout food products. Ethanol oxidase is another enzyme with oxygen sca- venging potential. It oxidizes ethanol to acetaldehyde. It has been in use as a breath alcohol analyzer test, but there is no known application for food (Labuza and Breene, 1989). 18 Synthetic "he-e" Scavenger Aquanautics Corporation has developed oxygen binding "heme” complexes which function well with high water activity food products and C02 environments (Zenner and Salame, 1989). The complexes are called LONGLIFEG and their chemical structures mimic that of a heme molecule. The complexes are water soluble and so were necessarily immobilized on silica and other supports. As a fixture of the crown closure, they have been successful in reducing oxygen concentration in a package of aqueous solution from over 2000 parts per billion (ppb) to less than 50 ppb within 24 hours. The absorber need not be in contact with the liquid to be effective. WW Snowden potatoes were harvested in the fall and stored at 13°C for at least two weeks before processing. Processing potatoes into potato chips consisted of washing the potatoes in cold water, abrasion peeling the potatoes for 30 seconds, slicing the potatoes to 1.5 millimeter-thick slices (1 0.25 mm), rinsing the slices in three batches of fresh, cold water, patting slices dry for over one minute, frying each batch until it stopped bubbling (2 to 3 minutes), and spreading the chips out on paper towel to dry before packaging. Potatoes for an entire day's processing were washed, peeled, and sliced in one batch. Fryer batches were about 210-230 grams each. All potatoes remained submerged in cold water between the stages of initial washing and patting dry for frying. Fully refined soybean oil was used for frying. The soybean oil had added TBHQ and citric acid to preserved stability and methyl silicone to inhibit foaming during frying. Fresh oil was poured for frying at the start of each processing day and oil was added as needed throughout the day. All oil came from the same lot number for all processing days. 19 W The initial moisture content of freshly fried potato chips was determined using a modified vacuum-oven method. Two to three gram samples (accurately weighed) of fresh, dry chips were placed in aluminum weighing dishes and dried in the vacuum oven under conditions of 30 mm Hg vacuum and 100°C for seven hours. After the vacuum was released, samples were placed in a desiccator until they cooled to room temperature at which time they were weighed. The equation (mi-wt) wan x 100 (2) where W1 = initial weight of chips and Wf = dried weight of chips was used to calculate moisture content on a dry basis. The reported initial moisture content is the average of nine samples. W A sorption isotherm was developed to determine the equilibrium moisture content (EMC) of the potato chips at different water activities (aw). Salt solutions were developed using the procedure described in Hygrodynamics Technical Bulletin No. 5 (Creating and Maintaining Humidities by Salt Solutions) and placed in seven tightly sealed, reclosable plastic buckets, creating constant relative humidity environments. The bucket environments equilibrated for two weeks before testing began. Isotherm 20 21 data were obtained gravimetrically by measuring product weight change over a two week period in constant temperature and relative humidity. Fresh chips were weighed accurately into tared aluminum weighing dishes on an analytical balance. The samples were then placed into the humidity buckets and weighed at intervals until they reached equilibrium weights for their respective environments. All humidity conditions inside storage containers remained constant as indicated by hygrometer sensors installed in each bucket. Temperature in the storage area was measured at 23°C t 2°C. Three samples were placed in each humidity bucket and the average EMC is reported. Macias Chips were dried in the open air for 30 to 120 minutes before packaging. Over 30 grams of chips were put into metallized polyester and metallized polypropylene bags. Oxygen absorbers were added to some bags. Bags were vacuumed, flushed with a specialty gas of the desired composition, and sealed on a Smith Super Vac vacuum packager, model GK 165R. Eight different groups were developed. Four groups had metallized polyester packages. Two of these groups were flushed with nitrogen and two were flushed with a 2% oxygen/98% nitrogen specialty gas from Liquid Carbonic. One group of each atmosphere had an oxygen absorbing label, 22 capacity 200 cc, dropped into the package. Four groups had metallized polypropylene packages. Two of these groups were flushed with a 2% oxygen/98% nitrogen specialty gas from Liquid Carbonic and two were flushed with a 10% oxygen/90% nitrogen specialty gas from Liquid Carbonic. One group flushed with the 2% oxygen gas had an oxygen absorber of capacity 200 cc dropped into each package and one group flushed with the 10% oxygen gas had an oxygen absorber of capacity 400 cc dropped into each package. The materials, initial oxygen concentrations, and use of absorbers for the eight groups are shown in Table 1. Table 1 Packaging Characteristics of Different Groups group Mini InitiaLthl Magenta: 1 metallized polyester 0% no 2 metallized polyester 0% yes 3 metallized polyester 2% no 4 metallized polyester 2% yes 5 metallized polypropylene 2% no 6 metallized polypropylene 2% yes 7 metallized polypropylene 10% no 8 metallized polypropylene 10% yes After sealing, bags were inflated with the appropriate gas supplied by Liquid Carbonic. Gas cylinder regulators were connected to needles by teflon tubing and after flushing the tubing with the appropriate gas, the needles were inserted through septa attached to the bags and the bags were inflated until they were firm. Septa attached to the bags were made of clear, circular, silicone dabs with 23 radii of approximately 8 millimeters and thickness of approximately 5 millimeters adhered to a section of electrical tape. W Water vapor transmission rate was measured gravi- metrically. Approximately 100 grams of desiccant was added to three bags of each material. The bags were heat sealed and weighed. Three empty bags of each material were also heat sealed and weighed. Packages were stored at conditions of 72°F and 50% relative humidity. Packages were weighed every two to three days until a constant rate of moisture gain was obtained. The net moisture weight gain was equal to the difference in weight over time of the packages with desiccant minus the difference in weight of the empty, control packages. The net weight gain was plotted as a function of time. The slope of the straight line portion of the graph equals the water vapor transmission rate for each package (WVTRP). The water vapor permeability of each package (Pp) was calculated using the following equation: Pp (g/package/day/mmHg) = WVTRp/[S(R1’R2)/100] (3) where 8 equals the saturation vapor pressure at test temperature and R1 and R2 equal the relative humidity of the external and internal package environments, respectively. 24 We The weights of chips prior to packaging and directly after were recorded. The weights of chip packages were taken at one or two week intervals for the first few months. Weights of chip packages were taken just prior to destruction for hexanal measurement. This allows measurement of the moisture content of the chips over time, which would correspond to their water activity level over time. YQIHI!_IQEEBIQIQI§ The volume of each inflated bag was measured by submersion in water. Each bag was submerged and the water displaced ran into a graduated cylinder for measurement. The volume of each bag was measured within the first 24 hours after packaging and at the time of destruction. Wages Headspace oxygen concentrations were measured with an Illinois Instruments Inc. model 3500 headspace oxygen analyzer. A sampling needle connected to the instrument by a tube was inserted through the septum into each bag. The bag was squeezed to produce a flow rate of approximately 0.05 liter/minute and the oxygen concentration was displayed by the instrument. The oxygen concentration of the headspace was measured on all bags within the first 24 hours 25 after packaging and at the time of destruction. Selected bags from each of the groups with oxygen absorbers were sampled for headspace oxygen concentration periodically over the first few weeks and not used for any other purpose. EEQISQQ All bags were stored hanging by clothespins on large wooden drying racks in an environmentally controlled room. The bags were hung by the material outside of their seams so that the pouch part of the bags did not touch other bags or the rack. The storage environment was monitored using a portable hygrometer. Temperature and relative humidity were constant at 73°F 1 2°F and 50% RH i 2%. Light exposure was variable in the storage area. The storage arrangement is shown in Figure 2. 26 Storage Arrangement of Potato Chip Packages Figure 2 W Apparatus for Trapping of Volatiles A gas flushing/volatile trapping system was designed. A cylinder of compressed nitrogen was connected to 3 flow meters through a series of copper tubing. The flow meters were each connected to a test cell by a combination of copper tubing and tygon tubing. The test cell consisted of a modified gas washing tube and a 450 milliliter (ml) Erlenmeyer flask modified to fit the dispersion tube without leaking. The exit tube of the dispersion tube is a ball joint. A pyrex cylinder trap 11 centimeters long with an inside diameter of 0.6 centimeters and a socket joint end was connected to the ball joint of the dispersion tube by a spring-loaded clamp which held the joint tight so no volatiles would be lost to the atmosphere. The apparatus without the trap attached is shown in Figure 3. 27 28 Figure 3: Apparatus for Trapping of Volatiles Trapping of volatiles Approximately 10 grams of chips weighed accurately were placed in the test cell. The test cell was closed tightly and the trap connected. Each trap was packed with four grams 1 0.1 grams Tenax-GR (80/100 mesh) between wadded pieces of glass wool. The test cell was then placed in a water bath and covered with aluminum foil to block out light. Nitrogen was flushed through the test cell and Tenax trap at an approximate rate of 25 cubic centimeters (cc) per minute for 22 hours. The test cell was flushed at room temperature for the first hour to remove oxygen from the cell before heating to minimize further oxidation. After one hour the water bath was turned on and allowed one hour to equilibrate to 70°C. The water bath remained at 70°C for the next 20 hours of flushing. Extraction and Concentration Procedure The extraction and concentration procedure was developed by Berends (1993). One microliter (pl) of HPLC grade 2-methylbutane (Aldrich Chemical Co., Milwaukee, WI) was injected into the gas chromatograph to ensure its purity before it was used to wash the hexanal from the pyrex traps. The Tenax traps were placed into a single hole cork stopper that was placed into the end of a 25 m1 graduated centrifuge tube. Using disposable transfer pipettes, 1 ml of 2- methylbutane (isopentane) was pipetted into the socket end 29 30 of the Tenax trap. The centrifuge tube was then placed in a centrifuge to accelerate the extraction of hexanal from the Tenax. The centrifuge (International Equipment Co., Boston, MA) was set at 500 revolutions per minute for 2 minutes, foreing solvent containing hexanal to the bottom of the graduated centrifuge tube. A 1.0 - 1.5 ml aliquot of isopentane was pipetted into the Tenax trap and it was centrifuged again. This was repeated a third time. Three to four ml of extractant were collected in the bottom of the centrifuge tube. Nitrogen was used to concentrate the hexanal by evaporating the extractant to a volume of 1.0 ml. This enabled trace amounts of hexanal to be detected by the gas chromatograph. The one ml in the centrifuge tube was quickly transferred to a 1.8 ml Supelco Screw Cap Vial with a Hole Cap and Septum. The vials were stored in the freezer to prevent evaporation of the isopentane and concentration of the sample. After hexanal was removed, Tenax traps were rinsed with isopentane, centrifuged, and baked in a 100°C oven for more than 12 hours. Tenax was reused four times and then removed. When Tenax was removed the glass traps were washed, rinsed with isopentane, dried in a 100°C oven, cooled, and refilled with fresh Tenax-GR and conditioned. 31 Percent Recovery of Hexanal Prom Tenax and Concentration Technique A recovery study was done to determine the percentage of hexanal that is recoverable from the extraction and concentration procedure. Two solutions of hexanal in isopentane were made and tested in duplicate to determine the percent recoverable. A 0.9 ul aliquot of each solution was injected into the programmed GC in triplicate. An average area response was used as a basis for 100% recovery. One milliliter of each solution was injected into a pyrex trap packed with freshly conditioned Tenax-GR. Then the extraction and concentration procedure was followed. A 0.9 ul aliquot of each extract was injected into the programmed GC. Injections were done in triplicate. The area responses of the three injections for each extract were averaged. The averages were divided by the area response set as a basis for 100% recovery for that solution to determine the percent recovery using this technique. Gas Chromatography A 5 ul syringe (Hamilton Co., Reno, NV) was placed in a freezer to cool. 0.9 ul aliquots of sample were injected with the cooled syringe into a Hewlett Packard gas chromatograph (GC), model 5890, equipped with a 60 meter Supelcowax 10 capillary column and a flame ionization 32 detector (FID). Standard solutions of hexanal in acetonitrile were made prior to injection of samples to ensure consistency of the GC's response. A Hewlett Packard 3392A integrator was interfaced with the GC. The conditions of the GC were programmed at an initial temperature of 40°C for one minute followed by heating at a rate of 5°C per minute to a final temperature of 150°C which was held for 10 minutes. The injection port temperature was 250°C. The range was set at 2 and the attenuation at 0. Hexanal Calibration Curve Development Procedure The standards made up for the calibration curve consisted of hexanal and acetonitrile (used due to low boiling point of isopentane). Volumetric flasks used for the procedure were washed, rinsed with distilled water, rinsed again with acetonitrile, and dried in a 100°C air oven. While the flasks were drying, the purity of the acetonitrile was evaluated using the GC. The GC conditions were programmed for an initial temperature of 40°C to be held for 1 minute and then increasing to a final temperature of 150°C at a rate of 5°C per minute. The final temperature was held for 10 minutes. The injection port temperature was 200°C and the detector temperature was 250°C. The range was set at 2 and the attenuation was zero. Three 0.9 pl injections of acetonitrile were made into the GC using the same 5 pl syringe. No peaks near the 33 retention time of hexanal were observed. After flasks were dry, they were removed and cooled to room temperature and labeled with their appropriate concentrations. 0.01 grams of hexanal were added to a 100 ml volumetric flask providing an initial standard solution with a hexanal concentration of 100 parts per million (ppm). 5 ml of 100 ppm solution were added to 5 ml acetonitrile in a 10 ml volumetric flask for a concentration of 50 ppm. 2 ml of 100 ppm solution were added to 8 ml acetonitrile in a 10 ml volumetric flask for a concentration of 20 ppm. 2.5 ml of 100 ppm solution were added to 22.5 ml acetonitrile in a 25 m1 volumetric flask for a concentration of 10 ppm. 2 ml of 100 ppm solution were added to 48 m1 acetonitrile in a 50 ml volumetric flask for a concentration of 4 ppm. 0.9 pl injections into the GC were made in triplicate from each flask using the same 5 pl Hamilton syringe. After each injection, the syringe was washed with acetone, and placed in a 100°C oven for 10 minutes to evaporate all residual solvent. The results from the three injections at each concentration were averaged and the average values were plotted. During the course of this study, the Supelcowax column was altered. Therefore, different calibration curves were created form the same standard solutions before and after altering the column. Appendix A contains the data and plots for both calibration curves. 2£2§R£&_l9§11 Potato chips fried in soy bean oil were packaged in metallized polyester and metallized polypropylene bags with and without oxygen absorbers and with varying initial oxygen concentrations. Potato chips are around 30 - 45% fat by weight (Orr and Cash, 1991) and soy bean oil is approximately 54% linoleic acid by weight. As mentioned earlier, linoleic acid is the predominant precursor of n- hexanal(Mantoba et al., 1985). This makes the product model around 16 - 24% linoleic acid which is the approximate oxidizing substrate concentration. The initial moisture content was experimentally determined and an equilibrium sorption isotherm was developed to determine the relationship between aw and the product model. The water vapor transmission rate, water vapor permeability, and the oxygen permeability of the two package materials were tested and calculated. Witnesses The temperature of the storage environment during the study normally fluctuated between 72 and 74°F. The temperature did reach a high of 78°F and a low of 66°F, but these temperatures were only sustained for brief periods. The relative humidity of the storage environment fluctuated 34 between 35 and 64%. These lows and highs were not maintained for more than 2 weeks at a time, and for the majority of the time, the relative humidity was near 48%. W The initial moisture content was determined using the following equation: IMC - (we/wd) *100 (4) where W6 a weight change (grams) W3 - weight of dry product (grams) Initial moisture content was 1.52g H§OI100 g dry product weight. Data and calculations are in Appendix B. W From the constant weight (average of triplicate weighings) that was obtained in each of the relative humidity conditions, the equilibrium moisture content was calculated according to the following equation: EMC = [Pf(l+IMC) [P11-1*100 (5) where: Pf - final product weight Pi 3 initial product weight EMC = equilibrium moisture content IMC - initial moisture content The sorption isotherm data are in Appendix C. Equilibrium moisture contents at the seven relative humidity environments are in Table 2. 35 36 Table 2 lguilibrium.loisture Contents at Each Water Activity W WW1: 0.10 3.16 0.21 3.76 0.32 5.46 0.41 5.98 0.51 7.89 0.71 13.29 0.83 23.26 A graph of the experimental sorption isotherm data is shown in Figure 4. 37 SORPTION ISOTHERM Fresh Potato Chips at 72F 8. 8 p—i U] I H O I 'JI I monolayer value 0 // 1 1 l 1 1 l 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Water Actmty Equilibrium Moisture Content, g H20/100g dry weight Figure 4: Sorption Isotherm W). W W The equilibrium sorption isotherm describes the water sorption characteristics of the product. The shape of the curve is a function of the sorption properties of the product. The resultant curve is usually sigmoidal in shape, and can be described by the BET equation among others. From the equilibrium sorption isotherm data, this mathematical model described a linear relationship between water activity and the product equilibrium moisture content up to a water activity of 0.41. Using Lotus 1-2-3, a statistical analysis was performed for the BET model and a correlation coefficient was calculated. The correlation coefficient estimated the degree of fit between the BET mathematical model and the experimental sorption isotherm. The constant in the BET model was calculated from the linearized form of the equation allowing for determination of the water activity at any product moisture content. The resultant linearized form for the BET model is aw/(m(1-aw)) = 1/Mic + aw(C-1/m1c) (1) and the correlation coefficient is 0.9931. The predicted equilibrium sorption isotherm values using the BET model versus the experimental values are given in Table 3. 38 39 Table 3 SET Model Expected values (1.) versus Actual Equilibrium Product Moisture Content values Water Experimental (Xe) % Difference 593.1211): EEC: 0.1 3.16 3.28 3.66 0.21 3.76 4.36 13.76 0.32 5.46 5.35 -2.06 0.41 5.98 6.31 5.23 0.51 7.89 7.73 -2.07 0.71 13.29 13.31 0.15 0.83 23.26 22.88 -1.66 Brunauer, Emmett, and Teller Monolayer value Using the data from the equilibrium sorption isotherm and the B.E.T. equation, the monolayer value was determined. The B.E.T. plot of aw (x-axis) versus aw/ng(1-aw) (y-axis) shown in Figure 5, yielded the linear regression equation: aw/uequ—aw) =- aw(0.2722) + 0.0050 (6) v.6 ed 2. 02m> 5.66:2). 0558560 5:211 5:2. ccm .LmEEm .5355 SS 58... 533 ad «6 To 9 _ d — ._.O.E ZO_wwmm0mm ._.mm ”m 059“. o 8s Se V m ) 8... \U _ w 8... M m 3 N3 3.: 41 Calculated x- and y-axis values for the B.E.T. plot are given in Table 4. Table 4 B.E.T. Regression Plot values for the Sorption Isotherm for Determining Monolayer value Water Activity x-axis y-axis _a.,_ mqllzawl .41 .41 .1164 .32 .32 .0862 .21 .21 .0706 .10 .10 .0351 Using the slope and y-intercept values form the B.E.T. regression equation, the monolayer moisture content was determined using the following formula: Monolayer Value = 1/(y-intercept + slope) The monolayer value was calculated to be 3.6089 Ric/100g dry product. The water activity corresponding to this value found from the sorption isotherm data is 0.197. WW3! The water vapor transmission rates (WVTR) of the two test packages were found to be 0.002707g/(day*package) for metallized polypropylene and 0.01584g/(day*package) for metallized polyester. Appendix D contains the individual weights of the desiccant and empty packages over time. Appendix E contains the individual weight gains of the desiccant and empty packages over time. The graph of the net weight gain as a function of time is shown in Figure 6. mm 00:08.2 9.500.000 Co 0E_.r L0>O £06 £903 0.2065. ”c 059“. 0m0xosd 050200 .00N___0..0_>_ . 098.on 05.306200 35:90.2 . 0200 c_ 08:. om m: S m o w _ _ _ o M e. 6 N 1 To 6 . m. .u 1 «.0 mm o _ H 1 0.0 I... .0. so _ Imsom .80 ”as 8 00930 D. mw00 22:0 ._.I_0_m>> m0< mg 43 A regression analysis was done on the straight line portion of the curves to determine the slopes and conse- quently the WVTR's. The data used in the regression analyses and the output of the analyses are shown in Table 5. The permeability constant for the metallized polypro- pylene package was found to be 0.000253g/(day*mmHg*pkg). The permeability constant for the metallized polyester package was found to be 0.001572g/(day*mmHg*pkg). Table 5 Water vapor Transmission Rate Data Time Moisture Weight Gain of Moisture Weight Gain of WWW 2 0.000067 0.025767 8 0.013533 0.117833 10 0.020400 0.156400 12 0.027233 0.195567 14 0.033200 0.235000 16 0.043600 0.260467 18 0.044800 0.290500 22 0.053700 0.358100 Line of Regression Output Wises Slope (WVTR g/(day pkg) 0.002665 0.016556 y-intercept -0.00392 -0.00545 Correlation Coefficient (R2) 0.978907 0.98097 thn.!sisbts The moisture weight gain of the potato chips in packages was measured gravimetrically. Using the initial moisture content average, the isotherm, and B.E.T. regression data, the moisture content of the chips over time and the corresponding water activities of the chips can be 44 calculated. A graph of the moisture content over time of chips packaged in metallized polypropylene and metallized polyester is shown in Figure 7. The weights of a representative sample of chip packages are reported in Appendix F. The weight gains of these chips over time are reported in Appendix G. The actual moisture contents of chips packaged in metallized polyester and metallized polypropylene were compared to computer generated expected values for moisture contents. The expected values were computed from a linear shelf-life model using the following inputted data: 1)temperature of 21°C, 2)IMC of 1.58% dry basis, 3)ERH of 5% for IMC, 4)MC at spoilage of 5.46%, 5)ERH of 32% at spoilage MC, 6)product weight of 31 g, 7)package area of 84 inz, 8)storage RH of 48%, and the water vapor permeability coefficients for each material. The computer predicted shelf lives of 179 and 1111 days for chips in metallized polyester and metallized polypropylene respectfully, if moisture content is the limiting factor. Figure 8 shows the actual and predicted values. The predicted values were low for the first 120 days and then high after that for the metallized polyester package. However, the linear shelf life model was very close to the actual for the metallized polypropylene package and may be useful in predicting the moisture content of unsalted potato chips in metallized polypropylene. 0:5 L0>O E0200 0.3065. 030 K 059”. .883. as. .3 82.502 x .2822 Sofia .E Basso: . sees. 55900 89:50: . .883. Boss; .50 Russo: _. swam E 08? com on“ OS om o 0.0 _ q _ H m a e x . a m L a m A a e o 0 a m 00 O E . a 1 m .m a m. 8880 05068 8.3688 Em a 0 a l v m. s d s Mb a P s l W n“ M w. o m mason m5 3 was... also 898 m=>__._. mm>O ._.Zm:.ZOO magma—2 00:_0> 00860.0 .m> 0020> .0304. ”08:. L0>O 2.0200 0.2065. 950 ”m 059“. 82.3 818.5 .322 a: 22m .5 x 83$ see... as . 83..» 83830. 362 as :25 .50 . 82$ .884. ems . when— E 08? com 03 OS on o a m _ H 3 x x xA x A x A Ax A i m x A x x x A x x x x x O 80 a L N m x x x x O 8 0 e s l on 0 0 a m w 0 0 a mu. 0 a s l v 1. . . _. m e s e s m. . f . 1 . a e e e e rm. w. on s m. mos—ear c080me 0002 as roam Leos: .m> 002.3 3301‘. m=>__._. mm>0 ._.Zm_._.ZOO mmDHQOE we IQIEI!.I£§1!£!I!D§ The volumes measured are only accurate to t 5 m1. As the initial volume measurement methodology was not tightly controlled, the volumes recorded as the initial volumes are less accurate than the final volumes. The volume data does show that even though the packages were inflated to firmness (pressurized), they did not lose volume over time. Initial and final volume measurements of bags are given in Appendix H. W The oxygen permeability of the two films, metallized polyester and metallized polypropylene, were measured using the mocon OX-TRAN 200. The oxygen permeability of the metallized polyester was measured at 0.6374 cc/100in2/day and the oxygen permeability of the metallized polypropylene was measured at 1.568 cc/100in2/day. Headspace Sampling of Oxygen For the groups with oxygen absorbers, headspace oxygen content was sampled daily until a low point was reached. All groups were sampled for headspace oxygen concentration upon destruction of bags for hexanal quantification. Figures 9, 10, 11 and 12 show the oxygen concentrations of the eight groups over time. The oxygen concentration data 47 48 over time for the eight groups is reported in Appendix I. For packages with absorbers, the data shows that as the initial oxygen concentration is raised, the time it takes for a package to reach a headspace oxygen concentration of 0% is shortened (assuming that the absorber capacity is adequate). nu cmmoEz 5:5 00:03.... 2.025 0098601 0200201 35:00.2 0:5 L0>O cozgcmocoo 5965 00000000: ”m 059... 8.2830 5s» . 0.2.830 o: a 983 s Base 09F on ma o2 comp—:2 an? poems—m 2:33 mowed—cam Sung—om coma—502 m _2 c. mm >0 2 O_._.XO m0mDO ZO_._.50 5:05:00 0:00: 0:800 U: 059... N1. 58025 .950 .2. 0050». 05.5 33 100008: 00 330000 m0.0 00.0 no.0 N00 20.0 0 _ d _ _ O w 1 on m. H 9 S u .m 0 1 n u 1; 0 m 9 e n 1 on m. m. ( 00m 00509004... E 30803 m>m30 ZO_._.¢ O0.0 H0.0 ON.O O0.0 hm.O hv.O NN.O Nm.O ON.O mH.O ON NH.H O0.0 M0.0 ON.O ON.O N0.0 Hm.O ¢¢.O hn.O ON.O OH.O OH b0.0 ON.O n5.0 O0.0 mm.O On.O Nm.O ON.O OH.O OH Om.O O0.0 Oh.O ON.O mw.O Nm.O v¢.O Om.O ON.O hH.O hH Oh.H Nh.H OO.H HO.H b¢.H OO.H ON.H ON.H NH.H NO.H OH H0.0 Hm.O O¢.O fin.O ON.O OH.O «H H¢.O nn.O ON.O nH.O nH Hn.O OH.O NH H0.0 NN.O O0.0 mm.O O¢.O mm.O ON.O ON.O HH mn.O mm.O ON.O MH.O OH NH.H O0.0 «0.0 ON.O Nh.O H0.0 m¢.O m¢.O ON.O mN.O MH.O m O0.0 ON.O ON.O mw.O mm.O vv.O H¢.O On.O OH.O O0.0 O v0.0 vm.o N¢.O ON.O ON.O mH.O h OO.H Hm.O m0.0 eh.O Hb.O O0.0 Hm.O mn.O Nn.O NN.O ¢H.O O OO.H Nm.O M0.0 ON.O O0.0 mm.O ¢¢.O mm.O ON.O bH.O m OO.H Om.O ¢0.0 O0.0 h¢.O hm.O ON.O mH.O e H0.0 N0.0 Oh.O O0.0 mm.O ¢¢.O nn.O ON.O VH.O m O0.0 mm.O O¢.O vn.O NN.O «H.O N N¢.O mn.O ON.O bH.O H «malxuq «aluma maluua muluuq Nuluua aqlxma 001000 .mmluma 00:00a 00:00a ulxua «000 0o «0 an noun-00om 000000000: 00 oo0oaoom 00000 ououom 0o .0. 00000 000000 00 000001» 00000 ououom no 00000 000000 0 NHQIIQQ‘ #O h¢.O NN.O ON.O HN.O ON.O OH.O O0.0 :Hmw .>4 O0.0 O0.0 ON bn.O O0.0 OH.O O0.0 OH ON.O OH.O hH.O HH.O H0.0 OH mm.O HN.O NN.O OH.O ¢0.0 bH On.O NN.O OH.O OH HN.O OH.O OH.O OH.O O0.0 OH ON.O OH.O NH.O O0.0 N0.0 OH O0.0 b0.0 O0.0 OH ON.O O0.0 O0.0 NH Om.O ON.O NN.O OH.O ¢0.0 HH OH.O OH.O HH.O N0.0 OH ON.O ON.O OH.O O0.0 O NH.O OH.O O0.0 O0.0 O O0.0 O0.0 O0.0 vn.O b ON.O OH.O HN.O OH.O O OH.O HN.O OH.O «0.0 m «0.0 ON.O NN.O NH.O O NN.O ON.O OH.O O0.0 m vN.O ON.O ON.O N v:. OH. O hH. O HH. O HO. O H «MAINua wMHINma qwluma Adlsma «mlxma dalxma aluma wmmn 03.039. on 50.. 0o 00 an noun-00om 000000000: 00 vo0-uoom 00000 ouooom 0o .0. 000-0 0000.: 00 onmma naHno eunuch no cad-u #:0003 O HHfllflhh‘ mO OO.H M0.0 hb.O O0.0 O0.0 mm.O O0.0 nn.O ON.O hH.O O0.0 CWMU . >¢ O0.0 ON.O ON.O O0.0 O0.0 O0.0 H0.0 Om.O ON.O OH.O O0.0 ON On.O ON.O NH.O O0.0 OH O0.0 Oh.O O0.0 O0.0 O0.0 nm.O ON.O OH.O O0.0 hH O0.0 ON.O ON.O O0.0 O0.0 O0.0 nn.O NN.O OH.O O0.0 OH O0.0 OH.O ON.O NN.O h0.0 OH On.O ON.O ON.O OH.O OH On.O ON.O OH.O b0.0 NH O0.0 n0.0 Ob.O Hb.O O0.0 O0.0 On.O On.O ON.O h0.0 HH N0.0 ON.O ON.O OH.O h0.0 OH O0.0 Oh.O O0.0 N0.0 N0.0 N0.0 On.O ON.O OH.O O0.0 O O0.0 ON.O Hb.O O0.0 O0.0 O0.0 nn.O ON.O OH.O h0.0 O ON.O O0.0 O0.0 N0.0 O0.0 nm.O ON.O hH.O O0.0 h h0.0 O0.0 bN.O O0.0 O Mb.O O0.0 N0.0 N0.0 hm.O On.O ON.O OH.O O0.0 O OH.O ON.O OH.O h0.0 O H0.0 M0.0 ON.O O0.0 O0.0 O0.0 hn.O ON.O ON.O O0.0 m OO.H ON.O ON.O O0.0 O0.0 H0.0 H0.0 Hn.O ON.O OH.O M0.0 N NO.H Oh. O Oh. O OO. O HO. O O0.0 OO. O ON. O ON. O HH. O HO. O H «mfllflud ONINMG ddluud Nwlfima MOINMG mdlxma mdlflma NM Nun OMINOQ mleud aINma MNI mm 0o «a an noquNHom OOuHHHauOI aw oouuxoam 050:0 ouduon no .0. undue annual 00 05mm. 00000 ououom no 00000 000000 0 NHQIIQQ‘ OO O0.0 O0.0 O0.0 O0.0 N0.0 ON.O ON.O ON.O HH.O b0.0 ON.O 6N IHA‘H OH.O hN.O ON.O NN.O ON.O OH.O NH.O ON.O ON.O ON.O OH.O OH.O O0.0 ON.O NN.O ON.O NH.O OH.O OH.O NH.O NH.O ON.O HN.O ON.O NN.O OH.O OH.O HN.O HN.O OH.O OH.O NH.O O0.0 OH.O ON.O ON.O OH.O OH.O OH.O HH.O HH.O OH.O OH.O OH.O OH.O HH.O OH.O OH.O OH.O OH.O O0.0 O0.0 O0.0 OH.O OH.O NH.O O0.0 OH.O N0.0 h0.0 M0.0 N0.0 N0.0 O0.0 N0.0 O0.0 h0.0 H0.0 O0.0 H0.0 O0.0 n0.0 h0.0 N0.0 H0.0 :Hmw . O30 om OH OH 00 OH OH OH nH NH HH HNMMWI‘QO‘S «nanuma uaalaua annuma 00|00a «mlxma malxma aluma wmmn guano-04 an 0000.00 «0 so noun-00o0 00000000.: 00 oo0-uoom 000:0 ououom 0o .0. 0:000 00000: O NHfliWfimd 00000 oaouom no 00000 «0000- NO 00.0 00.0 00.0 00.0 00.0 00.0 00.0 00.0 :Hmw .O>< O0.0 O0.0 O0.0 00.0 cm 00.0 00.0 00.0 0H 0H.0 00.0 00.0 0H 00.0 00.0 H0.0 00.0 OH. NN.O O0.0 O0.0 N0.0 OH ON.O O0.0 O0.0 N0.0 OH 00.0 N0.0 0H HN.O O0.0 O0.0 O0.0 O0.0 HH O0.0 00.0 00.0 N0.0 00.0 0 O0.0 O0.0 O0.0 00.0 N0.0 O H0.0 0 00.0 H0.0 H0.0 0 N0.0 N0.0 0 bH.0 O0.0 N0.0 O0.0 N0.0 00.0 N 00.0 H0.0 H «wdluua ONHINQG ONINua afluflud «NINMQ ONINMQ HHINMQ ulxmd INI U‘ M an 0o 00 an OQOHhaounhHom OOuuHH1008 :0 000-8010 uaHno eunuch we .0. 0:000 9:000: 00 owmmu. 00000 ououon no 00000 00000- 9 ”Hallmfid OO ON.O HH.O 00.0 00.0 00.0 O0.0 N0.0 CHMO .030 0H.0 00.0 00.0 O0.0 00 00.0 00.0 00.0 H0.0 0H O0.0 O0.0 O0.0 0H 00.0 00.0 00.0 00.0.. 0H O0.0 00.0 O0.0 00.0 N0.0! OH 0.0.0 00.0 00.0 00.0 H0.0: OH OH.O 00.0 00.0 O0.0 OH HH.O O0.0 00.0 O0.0 N0.0 0H 0N.0 0N.O NN.O 00.0 NH O0.0 N0.0 N0.0 HH O0.0 O0.0 O0.0 00.0 H0.0! 0H H0.0 N0.0 N0.0 O0.0! 0 O0.0 O0.0 00.0 O 00.0 O0.0 00.0 00.0 0 00.0 00.0 H0.0 00.0: O OH.O O0.0 00.0 N0.0 00.0I O b0.0 N0.0 N0.0 00.0 00.0 0 00.0 O0.0 N0.0 N0.0! N 00.0 H0.0 00.0 00.0 N0.0I H gland a; uwlflmd H13 and gland find NI mm 03.305. 5. 50.. 0o «0 an 000000o0000o0 000000000: :0 vo0ououm 00000 ououom 0o .0. 0:000 00000- 00 00.02% 00000 ououom no 00000 000000 0 NHDIUQQ‘ OO .0 00.00% 00000 ououom no 0:000 0000.: G NHDIflhfld O0.0 O0.0 00.0 N0.0 O0.0 O0.0 00.0 O0.0 N0.0 0O O0.0 O0.0 00.0 H0.0 O0.0 O0.0 00.0 O0.0 00.0 O0.0 H0.0 00.0 O0.0 00.0 00.0 O0.0 H0.0 O0.0 O0.0 N0.0 O0.0 N0.0 00.0 H0.0 N0.0 N0.0 00.0 2000 .O>< 00.0 00 OH 0H OH 00.0 OH N0.0 OH 0H O0.0 HH 00.0 0 N0.0 O h H0.0 O N0.0 0 00.0 N H0.0 H le «NINMG dNINfld ddlfldd WINMQ 0o aoH an OQOthounhHom vauwHHI»OI a0 0.0.30.0 onHao ounaom no .0. onHIo uaOHOI U‘ 0 m HH.O HH.0 00.0 00.0 0H.0 O0.0 :How .O>¢ 00.0 0H.0 00 O0.0 O0.0 OH O0.0 00.0 00.0 OH 00.0 00.0 00.0 0H O0.0 00.0 O0.0 OH 0H.0 HH.0 0H.0 OH 00.0 HH.O 00.0 OH O0.0 00.0 0H 0H.0 0H.0 00.0 NH OH.O 00.0 HH.0 0H.0 HH O0.0 O0.0 O0.0 OH 00.0 H0.0 H0.0 0 O0.0 00.0 O ~0.0 H0.0 H0.0 0H.0 0 00.0 HH.0 00.0 O 0H.0 OH.O NH.O 00.0 0 0H.0 00.0 0H.0 00.0 m O0.0 O0.0 H «wdlflua ONH Nun Hdluud «dlfiua ONINMG “laud mwl om uonuo-nn :0 0000.0o 000 on 000000o0000o0 00.000000: :0 oo0uuo00 00000 ououom 0o .0. 0:000 00000- 00 000mm 00000 ououom no 0:000 000000 0 NHOIflhmfl HO 92 LPPIIDIX H Tabla 32 Initial and Final volunon ot Potato Chip Package: of latallinad Polyontar Inflatad with nitrogan Eagxng§_nnmhez Initial_xglnn2_1221 Ein§l_yglnne_1221 2 940 910 3 815 390 4 840 880 7 920 900 8 835 910 9 800 970 11 830 1000 14 890 940 18 920 370 19 915 920 20 820 910 **i.bi. 33 Initial and final voluaon ot Potato Chip Paokaqon of Iotallinad Polyaatar Intlatod with Nitroqan and Paokaqad with Oxygan Abnorharn Eggknge_nnmh§: Initial_yglgm2_1221 Ein§l_yglnm§_1221 1 860 950 2 730 760 4 965 970 9 860 940 10 800 850 11 910 855 12 925 930 14 910 970 15 810 810 16 760 910 17 855 900 18 790 880 19 820 820 93 APPENDIX E Tabla 34 Initial and Pinal volunoa of Potato Chip Paokagoa of notalliaad Polyaatar Intlatod with 2% Oxygon/98% Nitroqan WWW 1 860 940 2 905 910 3 975 940 5 885 890 6 920 910 7 940 950 9 900 890 10 840 830 14 960 960 17 880 890 20 920 930 T351. 35 Initial and Pinal volunaa of Potato Chip Paokagaa of notalliaod Polyaatar Inflatad with 2% Oxygon/98% Nitroqon and Paokagod with Oxygon Abnorhora WWW 2 790 790 3 875 950 6 830 920 7 890 830 8 ' 885 940 9 810 905 12 835 940 15 850 960 16 850 805 17 835 920 18 840 1000 20 930 930 94 APPlflilx H 53513—56 Initial and final voluaaa of Potato Chip Paokagaa of Iotalliaad Polypropylana Inflatad with 2* Oxygan/98% litrogan W W W 1 670 790 2 860 940 7 880 850 8 845 870 9 845 890 11 760 820 13 810 830 14 875 860 15 840 810 17 860 910 18 945 960 T O 37 Initial and final volunaa of Potato Chip Paokagoa of lotalliaad Polypropylano Intlatod with 2% oxygan/PBt litrogon and Paokagod with Oxygan Abaorhora W W W 1 620 820 2 585 850 3 485 770 4 640 850 5 530 820 6 590 810 10 585 750 11 595 850 12 555 780 13 555 750 14 670 780 15 595 850 16 540 730 20 660 820 95 APPENDIX E T o 38 Initial and Pinal volunoa of Potato Chip Paokagoa of Iotalliaod Polypropylano Intlatod with lot Oxyqon/90% Nitrogen WWW 1 840 830 3 760 870 4 820 830 5 630 760 6 850 825 7 705 805 8 730 710 9 850 820 10 760 890 11 550 590 12 680 780 13 680 730 14 830 975 15 730 730 16 775 900 17 870 855 18 810 890 19 690 680 20 830 890 96 APPENDIX E Tabla 39 Initial and Pinal volunoa of Potato Chip Paokagaa of natalliaod Polypropylona Inflatad with 10% Oxygan/sot litrogan and Paokagod with Oxygan hhaorhora W 111W W). 2 750 840 3 680 720 4 770 870 9 710 850 10 755 840 11 710 890 12 640 750 13 660 910 14 705 720 16 615 750 17 760 810 18 685 850 20 675 800 97 APPENDIX I naadapaoo anyqan Conoantration ova: Iina *iablo 4o hwarago noadapaoo Oxygan Conoantrationa (%) of Iotalliaod Polyoatar Paokagaa ovor Tina 0% 02 Flushed 2% 02 Flushed ELADEQIDQI 2L9_Ah§2199: nLAhagzhgz 0.1655 0.0722 2.262 2.12 0.0989 0.8238 0.1059 0.2267 0.092 0.0582 0.08295 0.0444 0.0503 0.03128 0.0402 0.01796 0.0134 0.00046 0.0085 2.667 4.103 0.0296 0.0000 0.08482 0.2633 5.663 0.3263 4.31 0.1805 0.1323 7.99 7.1 3.77 1.264 8.355 0.8827 10.93 2.284 10.32 3.52 10.47 6.26 naadnpaoo Onyqan Conoantration ova: Tina 98 APPENDIX I mo 41 Avorago noadapaoo Onygon Conoantrationn (%) of lotallinod Polypropylana Paokagan ovor Tina 3.493 10.9 12.14 2% 02 Flushed W 1118;252:129: 2.298 2.096 0.971 0.2403 0.374 0.0188 0.00278 0.00000 0.00000 0.00000 0.0723 0.3167 0.0000 0.2775 0.166 0.0000 8.13 10% o2 Flushed 9.998 11.083 11.873 11.593 12.24 15.9 13.96 17.36 14.14 9.641 0.7204 0.03902 0.01404 0.00092 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 99 APPENDIX J Potato Chip nananal Data T351. 42 Hexanal Data for Pranh Chipn Sampling Chip Average Time Weight Area Area Area 1199116.). _L9.L_Beap_fl 8929.8 32:92:15.9 0 10.0212 2460 2460 2460 0 10.1119 1692 1427 1559.5 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex WWMWMM 0 0.00095 2.35e-O9 0.000002 0.246371 0.211122 0 0.00093 1.656-09 0.000002 0.175874 100 APPENDIX J Potato Chip Hananal Data Tahla 43 Hananal Data tor Chipa in Hatalliaad Polyaatar; Sampling Time 1299391 4 4 4 13 13 13 22 22 22 Sampling Time 1999391 4 4 4 13 13 13 22 22 22 0% Initial 0,; Chip Without an Absorber Average Weight Area Area Area ._191__ B999_t1 B99n_tz B9999n99 10.0457 10.0817 10.0217 10.3495 10.292 10.1425 9.9719 10.0495 10.0877 1777 4023 2798 4911 3044 3444 4311 5010 4244 1561 4274 2803 4345 3207 3368 4363 4934 3788 1669 4148.5 2800.5 4628 3125.5 3406 4337 4972 4016 Inj. £1191m11 0.000925 0.000925 0.000925 0.000925 0.0009 0.0009 0.0009 0.0009 0.0009 Q Hex. In11191 1.74e-09 3.638-09 2.608-09 3.99e-09 2.85e-09 3.068-09 3.77e-09 4.258-09 3.53e-09 Q Hex. 19991191 0.000002 0.000004 0.000003 0.000004 0.000003 0.000003 0.000004 0.000005 0.000004 Q Hex. 199191.. 0.187713 0.389127 0.280934 0.417127 0.307823 0.335715 0.420304 0.47042 0.388606 Average Q Hex _1ung1 0.285925 0.353555 0.426443 101 APPENDIX J Potato Chip Hananal Data Tan. 44 Hananal Data for Chipa in Hatalliaad Polyaatar; 0% Initial 02;‘lith a locoo Capacity Ahaorhar Sampling Chip Average Time weight Area Area Area 1199891 494—89994; 899912 3991191199 6 10.1012 3353 3304 3328.5 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 10.0096 10585 9874 10229.5 22 10.0024 21496 20471 20983.5 22 10.061 8094 7798 7946 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex WWMWMM 6 0.000925 3.01e-09 0.000003 0.321673 0.321673 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 0.0009 4.06e-09 0.000005 0.450621 0.534409 22 0.0009 6.958-09 0.000008 0.772082 22 0.0009 3.458-09 0.000004 0.380526 102 APPENDIX J Potato Chip Hananal Data T351. 45 Hananal Data for Chips in latalliaad Polyaatar; at Initial Ozg‘Iithout an Ahaorhar Sampling Time 119.933.). 6 6 12 12 22 22 22 Sampling Time 113.9159). 6 6 12 12 22 22 22 Chip Average Weight Area Area Area .19)_B999_tl B99942 39999099 10.0206 3938 3912 3925 10.0824 5044 5000 5022 10.0792 4076 4127 4101.5 10.02755 6545 6572 6558.5 10.0299 8713 8332 8522.5 10.1864 7499 7541 7520 10.0816 5875 5522 5698.5 Average Inj. Q Hex. Q Hex. Q Hex. Q Hex MMWMM 0.000925 3.468-09 0.000004 0.373173 0.41673 0.000925 4.29e-09 0.000005 0.460288 0.0009 3.59e-09 0.000004 0.396098 0.50058 0.0009 5.46e-09 0.000006 0.605063 0.0009 6.956-09 0.000008 0.770287 0.658469 0.0009 6.19e-09 0.000007 0.675341 0.0009 4.81e-09 0.000005 0.529779 103 APPENDIX J Potato Chip Hananal Data Tabla 46 Hananal Data for Chipn in Hatallinad Polyaatar; 2% Initial 02;‘Iith a 200oo Capacity Ahaorhar Sampling Chip Average Time Weight Area Area Area 1999119). 4911—3999.91 899912 89999999 7 10.0366 2402 2354 2378 7 10.1513 4486 4427 4456.5 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 10.0221 10222 10506 10364 22 10.1873 23526.5 24700 24113.25 22 10.1318 8354 7768 8061 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex 119999191291911 MM—M 7 0.0009 2.289-09 0.000003 0.252759 0.254596 7 0.0009 2.346-09 0.000003 0.256434 DATA BELOW THIS LINE IS FOR THE SECOND 22 0.0009 4.108-09 0.000005 22 0.0009 7.798-09 0.000009 22 0.0009 3.48e-09 0.000004 CALIBRATION CURVE 0.454067 0.561719 0.849834 0.381257 104 APPENDIX J T351. 47 Potato Chip Hananal Data Hananal Data for Chipa in Iatalliaad Polypropylana; 2% Initial 033‘Iithout an Abaorhar Sampling Chip Average Time Weight Area Area Area 1199149). .191_B999J_1 3999.12 2 10.0018 2570 2692 2631 2 10.0027 2689 2729 2709 4 10.068 2953 2952 2952.5 10 10.0886 4782 4695 4738.5 10 10.0874 2642 2788 2715 10 10.2044 3497 3508 3502.5 22 10.0405 9487 10148 9817.5 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 10.2478 13334 13654 13494 22 10.0926 9930 10731 10330.5 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex 11991591 19991191199191—_1u9!_91 2 0.000925 2.48e-09 0.000003 0.267568 0.27076 2 0.000925 2.53e-09 0.000003 0.273951 4 0.000925 2.723-09 0.000003 0.292047 0.292047 10 0.0009 4.08e-09 0.000005 0.449051 0.356805 10 0.0009 2.54e-09 0.000003 0.279699 10 0.0009 3.14e-09 0.000003 0.341665 22 0.0009 7.94e-09 0.000009 0.878397 0.621199 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 0.0009 4.94e-09 0.000005 0.535297 22 0.0009 4.09e-09 0.000005 0.449904 105 APPENDIX J Potato Chip Hananal Data m Hananal Data for Chipa in Hatalliaad Polypropylana; 2% Initial 0,;‘Iith a 200cc Capacity Abnorhar Sampling Chip Average Time Weight Area Area Area 1199159). 4511—89994]. 89ml: 8991191199 8 10.0410 3868 3748 3808 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 11.1121 12881 12792 12836.5 22 10.2038 18565 18079 18322 22 10.3235 7236 6742 6989 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex MWMMM—M 8 0.000925 3.378-09 0.000004 0.362841 0.362841 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 0.0009 4.768-09 0.000005 0.475988 0.499361 22 0.0009 6.236-09 0.000007 0.678934 22 0.0009 3.198-09 0.000004 0.343161 APPENDIX J Potato Chip Haxanal Data *Tahla 49 Hananal Data for Chipa in latallinad Polypropylana; 10% Initial 02; Without an Ahaorhar Sampling Chip Average Time Weight Area Area Area 11991391 .191_B999_tl W 2 10.0954 2506 2168 2337 2 10.0575 1917 1933 1925 10 10.0798 5709 5727 5718 10 10.0506 5916 6107 6011.5 10 10.0024 4123 4127 4125 14 10.0366 3941 4187 4064 16 10.0184 4922 5174 5048 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 10.0794 15628 14565 15096.5 22 10.0350 11054 10644 10849 22 10.2494 23459 23315 23387 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex 1999391 1311191 19991191 199191.. .199191 2 0.000925 2.258-09 0.000002 0.241158 0.224783 2 0.000925 1.948-09 0.000002 0.208407 10 0.0009 4.82e-09 0.000005 0.531508 0.496781 10 0.0009 5.04e-09 0.000006 0.557713 10 0.0009 3.61e-09 0.000004 0.401123 14 0.0009 3.56e-09 0.000004 0.394623 0.394623 16 0.0009 4.31e-09 0.000005 0.478287 0.478287 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 0.0009 5.37e-09 0.000006 0.591729 0.627723 22 0.0009 4.238-09 0.000005 0.46792 22 0.0009 7.60e-09 0.000008 0.82352 107 APPENDIX J Potato Chip Hexanal Data T351. 50 Hananal Data for Chipa in Hatalliaad Polypropylana; 10% Initial Oag'Iith a 400cc Capapcity Ahaorhar Sampling Chip Average Time Weight Area Area Area 1199159). .191_B999_£l 8999.12 39999899 6 10.0963 3004 3695 3349.5 8 10.0415 3764 3205 3484.5 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 10.0941 6911 6651 6781 22 10.4600 7090 7180 7135 22 10.2446 6959 6559 6759 Sampling Average Time Inj. Q Hex. Q Hex. Q Hex. Q Hex 1199391 In11191 19991191 199191.. .1MQL91 6 0.000925 3.029-09 0.000003 0.323538 0.323538 8 0.000925 3.129-09 0.000003 0.336351 0.336351 DATA BELOW THIS LINE IS FOR THE SECOND CALIBRATION CURVE 22 0.0009 3.13e-O9 0.000003 0.344804 0.342251 22 0.0009 3.23e-09 0.000004 0.342852 22 0.0009 3.138-09 0.000003 0.339098 108 APPENDIX E T3510 51 Parcant Racovary Data 8 Calculation: Solution 1: Solution for Basic Extract 1 Extract 2 191999199 A:£§.B§§DQD§§ 5:99.32522293 5:29.39929359 24442 21576 23340 2 23260 18555 20608 3 22960 17404 21497 Average 23554 19178 21815 Recovery 81.4% 92.6% Average Recovery 87% Solution 2: Solution for Basis Extract 1 Extract 2 WWWW 9585 8617 8869 2 9121 8141 8400 3 9702 9385 8827 Average 9469 8714 8699 Recovery 92.0% 91.9% Average Recovery 91.9% LIST OF REFERENCES 109 LIST OF REFERENCES Anonymous. August 1990. The packaging activists. Prepared Foods. pp. 172. Berends, C.L. 1993. Measurement of the effect of water activity on the rate of lipid oxidation at constant oxygen concentration. M.S. thesis. Michigan State University, East Lansing. Bidlack, W.R. and Tappel, A.L. 1973. Fluorescent products of phospholipids during lipid peroxidation. Lipids. 8:203-207. Brunauer, 8., Emmett, H.P. and Teller, E. 1938. Adsorption of gases in multimolecular layers. J. Amer. Chem. Soc. 60:309-319. Buttery, R.G. 1961. Autoxidation of Potato Granules. Agricultural and Food Chemistry. 9(3):245-252. Cavaletto, C.G. and Yamamoto, H.Y. 1971. Factors affecting macadamia nut stability. 3. Effects of roasting oil quality and antioxidants. Journal of Food Science. 36:81. Columbus Instruments International Corporation. 1993. Lipid Peroxidation in Potato Chips. 1993 Promotional Leaflet. Columbus Instruments International Corporation, Columbus, Ohio. Fennema, O.R. 1985. Lipids. In Fbod Chemistry, O.R. Fennema (Ed.),23-67. Marcel Dekker, New York. Frankel, E.N. 1984. Lipid Oxidation: Mechanisms, products and biological significance. JAOCS. 61(12):1908-1915. Frankel, E.N., Neff, W.E. and Selke, E. 1981. Lipids. 16:279-285. Fritsch, C.W. and Gale, J.A. 1977. Hexanal as a measure of rancidity in low-fat foods. J. Amer. Oil Chem. Soc. 54:225-228. Fuller, 0., Guadagni, D.G., Weaver, M.L., Notter, G. and Horvat, R.J. 1971. Evaluation of oleic safflower oil in frying of potato chips. J. Food Sci. 36:43—44. 110 Gray, J.I. 1991. Measurement of Lipid Oxidation. Presented at AOCS short course on Lipid Oxidation, May 1992. Gray, J.I. and Monahan, F.J. 1992. Measurement of lipid oxidation in meat and meat products. Trends in food Science 8 Technology. 3:315-319. Gutteridge, John M.C. and Halliwell, Barry. 1990. The measurement and mechanism of lipid peroxidation in biological systems. TIBS 15 April 129-134. Heidelbaugh, N.D. and Karel, M. 1970. Effect of water binding agents on catalyzed oxidation of methyl linoleate. JAOCS 47:539. Heidelbaugh, N.D., Yeh, C.P. and Karel, M. 1971. Effects of model system composition on autoxidation of methyl linoleate. J. Ag. Food Chem. 19:140. Idol, R.C. and Wagner, B.F. Evolution of oxygen absorbers. Jeon, I.J. and Bassette, R. 1984. Analysis of n-Pentanal and n-Hexanal as Indices of Potato Chip Shelf-Life. J. of Food Quality. 7:97-105 Kail, J.A.E. 1984. Flavor Barrier Evaluation Enhances Material Selection. Packaging. Sept. 1984:68-70. Karel, M., and Yong, S. 1981. Autoxidation-initiated reactions in food. In water Activity: Influences on Fbod Quality, L.B. Rockland and G.F. Stewart (Eds.), 511-529. Academic Press, New York. Keener, John. 1994. Personal communication. Frito-Lay, Wooster, OH. Koelsch, C.M. 1989. A system for the measurement of the rate of lipid oxidation at constant oxygen concentrations and relative humidity. M.S. thesis. Michigan State University, East Lansing. Labuza, T.P., Tannenbaum, S.R. and Karel, M. 1970. Water content and stability of low moisture and intermediate moisture foods. Food Technology 24:543. Labuza, T.P., Heidelbaugh, N.D., Silver, M. and Karel, M. 1971. Oxidation at intermediate moisture content. JAOCS 48:86. 111 Labuza, T.P. and Breene, W.M. 1989. Application of "Active Packaging" for improvement of shelf-life and nutritional quality of fresh and extended shelf-life foods. Journal of Food Processing & Preservation. 13:1-69. Matoba, T., Hidaka, K., Narita, H., Kitamura, K., Kaizuma, N. and Kito, M. 1985. Lipoxygenase-z isozyme is responsible for generation of n-hexanal in soybean homogenate. J. Agric. Food Chem. 33:852-855 Melton, S.L. 1983. Food Technology. 37(7):105-111. Mookherjee, B.D., Deck, R.E. and Chang, 8.8. 1965. Relationship between monocarbonyl compounds and flavor of potato chips. J. Agric. Food Chem. 13(2):131-134. Nakamura, M. and Hoshino, J. 1983. Chapter XII. Techniques for the preservation of food by employment of an oxygen absorber. In Sanitation Cbntrol for Food sterilizing Techniques, Sanyo Pub. Co., Tokyo, Japan. Nawar, Wassef W. 1985. Lipids. In Food Chemistry, O.R. Fennema (Ed.), 139-244. Marcel Dekker, New York. Orr, P.H. and Cash, J.N. 1991. Potatoes and Potato Processing. In Encyclopedia of Ebod Science and Technology, 4 Volume Set. 2132-2136. Jon Wiley and Sons, Inc. Paradis, Armand. 1993. Personal communication. Liquid Carbonic, Chicago, IL. Quast, D. and Karel, M. 1971. Effects of oxygen diffusion on oxidation of some dry foods. Journal of Food Technology. 6:95-106. Quast, 0.6. and Karel, M. 1972. Effects of Environmental Factors on the Oxidation of Potato Chips. J. of Food Science. 37:584-588. Rice, J. 1990. Polymeric oxygen scavenger system. Food Processing. July 1990. pp. 44,46. Rooney, M. 1981. Oxygen scavenging from air in package headspaces by singlet oxygen reactions in polymer media. J. Food Sci. 47:291. Rooney, M. 1983. Photosensitive oxygen scavenger films: an alternative to vacuum packaging. CSIRO Fd. Res. Q. 43:9-11. 112 Sacharow, S. 1991. Packaging meets 19908 needs through active technology. Paper, Film & Foil Converter. July 1991. pp. 52-53. Scott, D. and Hammer, F. 1961. Oxygen scavenging packet for in package deoxygenation. Food Technology 15:99 Tang, J., Ma, M., Street, J., Warren, L., Schroeder, O.E. and Wohlman, A. 1981. Studies on potato chip flavor stability. J. Amer. Oil Chem. Soc. 58:576A (Abst.) Waletzko, P. and Labuza, T.P. 1976. Accelerated shelf-life testing of an intermediate moisture food. J. Food Sci. 41:1338. Zenner, B.D. and Salame, M. 1989. A new oxygen absorbing system to extend the shelf-life of oxygen sensitive beverages. Presented at BEV-PAK '89 Thirteenth International Ryder Conference on Beverage Packaging, April 3-5, 9.