Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1984 Kinetics of protein quality change in extruded cowpea:corn flour under varied steady-state storage conditions Mitchell Louis Ringe Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, and the Food Science Commons Recommended Citation Ringe, Mitchell Louis, "Kinetics of protein quality change in extruded cowpea:corn flour under varied steady-state storage conditions " (1984). Retrospective Theses and Dissertations. 8211. https://lib.dr.iastate.edu/rtd/8211 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. 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These prints are available upon request from the Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases the best available copy has been filmed. University Microfilms International 300 N. Zeeb Road Ann Arbor, Ml 48106 8505865 Ringe, Mitchell Louis KINETICS OF PROTEIN QUALITY CHANGE IN EXTRUDED COWPEA;CORN FLOUR UNDER VARIED STEADY-STATE STORAGE CONDITIONS Iowa State University PH.D. 1984 University Microfilms IntGr n clti O n Sll 300 N. zeeb Road, Ann Arbor, Ml48106 Kinetics of protein quality change in extruded cowpea:corn flour under varied steady-state storage conditions by Mitchell Louis Ringe A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Food and Nutrition Major; Food Science Approved; Members of the Committee: Signature was redacted for privacy. Signature was redacted for privacy. 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For the Gradate College Iowa State University Ames, Iowa 1984 ii TABLE OF CONTENTS PAGE INTRODUCTION 1 REVIEW OF THE LITERATURE 5 The Maillard Reaction 5 Discovery and significance 5 Chemistry of the Maillard reaction in model systems and foods 5 The early stages 7 •The advanced stages 11 The final stages 15 Physical and chemical factors effecting the rates of non-enzymatic browning 16 Analytical Methods for Quantitation of Maillard Browning 21 Quantitation of browning pigment 22 Available lysine after Maillard reactions in foodstuffs 23 Chemical methods for lysine 23 l-Fluoro-2,4-dinitrobenzene reactive lysine 25 2,4,5-trinitro-benzenesulfonic acid reactive lysine 28 Measurement of reactive lysine by guanidination 29 Reduction with sodium borohydride 29 The furosine method 29 Dye-binding methods 30 Biological methods 31 Microbiological and enzymatic methods for reactive lysine 31 In vivo methods for reactive lysine 32 Comparative studies between reactive lysine methods 33 The Effect of Maillard Browning Reactions on Nutritional Quality of Proteins 35 Application of Steady and Non-Steady State Kinetics to Changes in Reactive Lysine and Non- Enzymatic Browning 40 METHODS AND MATERIALS 44 Cowpea:Corn Powder Production 44 iii Crude Protein/Total Nitrogen 45 Trypsin Inhibitor Activity '. 45 Sorption Isotherm 45 Equilibration/Sample Preparation 47 Non-Enzymatic Browning 48 Reactive Lysine Determination 50 In vitro Protein Digestibility 51 Experimental Design 51 Statistical Analysis 53 RESULTS AND DISCUSSION 55 Crude Protein and Trypsin Inhibitor Inactivation ... 55 Sorption Isotherm Determination 57 Kinetic Analysis of FDNB-Reactive Lysine Losses ... 58 Individual variation in first-order rate constant estimation 58 Main effects of temperature and a„ on FDNB- reactive lysine loss 58 Temperature dependence of FDNB-reactive lysine losses in cowpea:corn flour under varied storage conditions 75 Kinetic Analysis of Non-enzymatic Browning Reactions 81 Nutritional Significance and Storage Implications . 85 SUMMARY AND CONCLUSIONS 91 BIBLIOGRAPHY 95 ACKNOWLEDGEMENTS 107 iv LIST OF TABLES PAGE TABLE 1. Crude protein content of the LEG processed cowpea:corn flour blend 55 TABLE 2. Change in trypsin inhibitor activity with LEG processing in the cowpea:corn flour food system 56 TABLE 3. Sorption isotherm moisture contents for cowpea:corn flour 57 TABLE 4. First order rate constants for FDNB- reactive lysine loss in LEG processed cowpea:corn flour under varied storage conditions 50 TABLE 5. First order rate constants (k) + S.E.M. for FDNB-reactive lysine loss in cowpea:corn flour under varied storage conditions 59 TABLE 5. Statistical analysis of FDNB-reactive lysine loss kinetics 71 TABLE 7. Temperature dependence of FDNB-reactive lysine loss in cowpea:corn flour under varied storage conditions 77 TABLE 8. Kinetics of non-enzymatic browning in LEG processed cowpea:corn flour stored at 55°C and a = 0.55 . .: 82 w TABLE 9. Tîj for FDNB-reactive lysine loss in LEG processed cowpea:corn flour under varied storage conditions 85 TABLE 10. Change in in vitro protein digestibility in LEG processed cowpea:corn flour after 15-21 wks storage under varied storage conditions . 89 V LIST OF FIGURES PAGE FIGURE 1. Initial stages in the Maillard reaction ... 8 FIGURE 2. The Amadori rearrangement 11 FIGURE 3. The Heyn's rearrangement 12 FIGURE 4. 1-2 Enediol degradation pathway 13 FIGURE 5. 2-3 Enediol degradation pathway 13 FIGURE 6. The Strecker degradation • 14 FIGURE 7. Sorption isotherm at 25°C for LEG processed cowpea:corn flour 59 FIGURE 8. FDNB-reactive lysine loss in LEG processed cowpea:corn flour at 25°C and varied a^ ... 52 FIGURE 9. FDNB-reactive lysine loss in LEG processed cowpea:corn flour stored at 35°C and varied a 64 w FIGURE 10. FDNB-reactive lysine loss in LEG processed cowpea:corn flour at 45°C and varied a^ ... 66 FIGURE 11. FDNB-reactive lysine loss in LEG processed cowpea:corn flour at 55°C and varied a^ ... 67 FIGURE 12, Arrhenius plot of steady state rate constants versus reciprocal of absolute temperature for a^ = 0.44 78 FIGURE 13. Arrhenius plot of steady state rate constants versus reciprocal of absolute temperature for a^ =0.55 79 FIGURE 14. Arrhenius.plot of steady state rate constants versus reciprocal of absolute temperature for a^ =0.65 80 vi FIGURE 15. Non-enzymatic browning in LEG processed cowpea:corn flour under storage at 55°C and a = 0.65 84 w 1 INTRODUCTION Even with the advent of increased individual and governmental support and awareness, the food crisis in less developed countries remains a significant problem (Berg, 1974). Central to this issue are concerns for both the quality and availability of food. .While a critical need exists for both calories and protein, questions concerning the amount and quality of dietary protein may be more important than energy (Scrimshaw, 1981). Solutions to food problems in less developed countries have generally been in the form of outside intervention and provision of foodstuffs, or outside assistance in economic and agricultural development. However, implementation of traditional processing technology is often not economically feasible for less developed nations (Jansen et al. 1978). Recently, low-cost extruder cookers (LEG) have been used for the development of cereal:legume blends intended for use in less developed countries (Jansen et al. 1978). The development and evaluation of a high-protein, nutritionally sound legume: cereal based weaning food supplement processed with LEC technology has been a recent accomplishment of this department. Despite the increased interest in the incorporation of LEC technology in less developed countries, there are relatively little data available to adequately