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University Microfilms International 300 North Zeob Road Ann Arbor, Michigan 48106 USA St John's Road, Tyler’s Green High Wycombe, Bucks, England HP10 8HR 77-31,902 KARDOSH, Kamal B., 1947- EFFECT OF SUBSTRATES ON THE FORMATION OF FUSEL ALCOHOLS IN A SIMULATED BEER FERMENTATION. The Ohio State University, Ph.D., 1977 Food Technology University Microfilms International, Ann Arbor, Michigan 4aioe EFFECT OF SUBSTRATES ON THE FORMATION OF FUSEL ALCOHOLS IN A SIMULATED BEER FERMENTATION DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Kamal B. Kardosh, B.Sc., M.Sc. The Ohio State University 1977 Reading Committee: Approved by W. H. Harper T. Kristoffersen E. Mikolajcik rtment of Food and Nutrition J. L. Blaisdell DEDICATION I wish to dedicate this dissertation to my parents Boulous and Yavon Kardosh for all the things they have meant to me. ii ACKNOWLEDGMENT Scientific journals and research papers dealing with beer technology and fermentation are markedly scarce throughout the United States' university libraries. At Ohio State University, the largest campus in the U.S.A., the libraries have no such journals as Technical Quarterly, Brewing Digest or The Brewing Institute Journal. In con trast, two large beer-producing companies with research facilities with which I was in contact, have excellent libraries equipped with many journals and books. I would have found it very difficult to have completed this research without the use of their facilities. In particular, I am grateful to Dr. Morten C. Meilgaard, Director of Research and Development, The Stroh Brewing Co., Detroit, Michigan, for all the help extended to me throughout my graduate work. I am also grateful to Ross Laboratories, Columbus, Ohio for their help in analyzing the ‘amino acids samples. I can not imagine, for a moment, that I could have com pleted this study without the help, advice, and encourage ment of many people. iii ACKNOWLEDGMENT (continued) To my faculty adviser, Dr. W. J. Harper, my sincere thanks and gratitude for his guidance and support throughout this endeavor. To the chairman of the department, Dr. Thorvald Kristoffersen, I am thankful for providing me with the opportunity to pursue graduate studies. Above all, Dr. Kristoffersen's help and guidance in preparing this manu- script were invaluable. To Dr*. Rory Delaney, the Department of Food Science and Nutrition, my many thanks for his generous cooperation and advice in preparing the experimental design in some of the experiments. I acknowledge the friendship and help extended to me by Drs. Emil Mikolajcik and Paul Hansen, the Department of Food Science and Nutrition. Also, to all the faculty members who made my stay at Ohio State a pleasant experience. To the graduate .students at this department, thanks for all the memories, the good times, and above all your friend ship. And last but not least, my love aiid thanks to my wife; Pamela, for her moral support and for her beautiful gift, our new baby, Adrienne Lee, born a few days prior to my final oral examination. iv VITA May 19, 1947 Born - Nazareth, Israel 1972 .... B.Sc., University of Wisconsin, La-Crosse, Wisconsin 1973-1975 . Graduate Research Associate, The Food Science and Nutrition Department, The Ohio State Uni versity, Columbus, Ohio 1975 .... M.Sc., The Ohio State University, Columbus, Ohio 1975-1977 . Graduate Teaching Associate, The Food Science and Nutrition Department, The Ohio State Uni versity, Columbus, Ohio 1977 .... Consultant Food Technologist Booz Allen and Hamilton Florham Park, New Jersey v TABLE OF CONTENTS Page DEDICATION .......... .................................. ii ACKNOWLEDGMENTS..........................................ill VITA ...................................................... V • LIST OF T A B L E S ............................ ix LIST OF FIGURES ....."......................... xii INTRODUCTION ......... 1 LITERATURE REVIEW ....................................... 3 Brewing Technology ............................ ‘ . 3 Effect of Steeping on Wort Amino Acids ........... 6 Effect of Steeping on Wort Carbohydrates ......... 8 Nitrogen Utilization .............................. 8 Carbohydrate Utilization .......................... 10 Flavor Compounds in B e e r ......................16 Factors Affecting the Production of Fusel Alcohols ................................. 1 7 Biosynthesis of Fusel Alcohols 22 Nutritional Properties of B e e r ............... 30 SCOPE OF INVESTIGATION ...................... *...........33 EXPERIMENTAL PROCEDURE . ......................... ; 34 Fermentation Medium and P r o c e s s ............. 34 Determination of Fu b b I Alcohols ......... 36 Determination of Individual Carbohydrates .... 40 Determination of Free Amino Nitrogen .........42 Determination of Amino Acids ........... 46 Determination of Ammonium S u l f a t e ...........47 Specific Gravity Measurements .......... 50 Analysis of Variance ............................ 5 1 Yeast Cell Count . ................................ 52 vi TABLE OF CONTENTS (continued) » Page RESULTS ............................. 53 Fusel Alcohols in Selected Samples of Commercial B e e r ............................ 53 Effect of Source and Concentration of Nitrogen on Selected Characteristic of B e e r ............................................. 54 A) Free Amino Acids ................. 54 Fusel Alcohol Formation . .................... 57 Carbohydrate Utilization .......... 59 Free Amino Nitrogen Utilization ............. 66 Amino Acid Utilization..........................66 pH and Specific Gravity ....................... 80 B) Ammonium Sulfate ....................... 80 Fusel Alcohol Production 84 ' Carbohydrate Utilization ............. .... 89 Ammonia Nitrogen Utilization .... ......... 89 pH and Specific Gravity ..................... 94 Comparison of Results for the Fermentations with Amino Acids and Ammonium Sulfate as the Source of Nitrogen ..............................94 Effect of Nitrogen Source on Free Amino Nitrogen Utilization . ...................... 102 Role of Carbohydrates on Selected Characteristics of B e e r ...........................102 Addition of Single Carbohydrate to Wort . .102 Fusel Alcohol Production ........... 104 Other Characteristics .........................106 Effect of the Ratio of Fermentable Carbohydrates in W o r t .............................106 Fusel Alcohol Production...................... 108 Carbohydrate Utilization ...................... 115 Ammonia Nitrogen Utilization .................. 119 pH and Specific Gravity . ................ 119 vii TABLE OP CONTENTS (continued) Page Periodic Addition of Carbohydrate to the W o r t .................................. .122 Fusel Alcohol Production .......................125 Carbohydrate Utilization...................... 125 Ammonia Nitrogen Utilization.................. 133 pH and pH Gravity ............................. 135 Yeast Cell Growth .......................135 DISCUSSION ............................................141 SUMMARY AND CONCLUSIONS................................. 158 BIBLIOGRAPHY ....................................... 162 viii LIST OF TABLES Table Page 1. Degree o£ Steeping at which Highest Levels of Amino Acids are Obtained in Eli M a l t ................................ 7 2. Degree of Steeping at which Highest Levels of Sugars are Obtained in Barley M a l t ..................................... 9 3. Order of Absorption of Amino Acids From Wort by Brewers' Y e a s t ........................ 11’ 4. Fusel Alcohol Content of Some Commercial Beer . ...............................