WHOLE-WHEAT FLOUR MILLING AND THE EFFECT OF DURUM GENOTYPES AND TRAITS ON WHOLE-WHEAT PASTA QUALITY A Dissertation Submitted to the Graduate Faculty of the North Dakota State University of Agriculture and Applied Science By Lingzhu Deng In Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Major Program: Cereal Science June 2017 Fargo, North Dakota North Dakota State University Graduate School Title WHOLE-WHEAT FLOUR MILLING AND THE EFFECT OF DURUM GENOTYPES AND TRAITS ON WHOLE-WHEAT PASTA QUALITY By Lingzhu Deng The Supervisory Committee certifies that this disquisition complies with North Dakota State University’s regulations and meets the accepted standards for the degree of DOCTOR OF PHILOSOPHY SUPERVISORY COMMITTEE: Dr. Frank Manthey Chair Dr. Senay Simsek Dr. Julie Garden-Robinson Dr. Elias Elias Approved: November 1st, 2017 Dr. Richard Horsley Date Department Chair ABSTRACT An ultra-centrifugal mill was evaluated by determining the effect of mill configuration and seed conditioning on particle size distribution and quality of whole-wheat (WW) flour. Ultra-centrifugal mill configured with rotor speed of 12,000 rpm, screen aperture of 250 μm, and seed conditioning moisture of 9% resulted in a fine WW flour where 82% of particles were <150 µm, starch damage was 5.9%, and flour temperature was below 35°C. The single-pass and multi-pass milling systems were evaluated by comparing the quality of WW flour and the subsequent WW spaghetti they produced. Two single-pass mill configurations for an ultra-centrifugal mill were used (fine grind: 15,000 rpm with 250 μm mill screen aperture and coarse grind: 12,000 rpm with 1,000 μm mill screen aperture) to direct grind durum grain or to regrind millstreams from roller milling to make WW flour and WW spaghetti. Particle size, starch damage, and pasting properties were similar for direct fine grind WW flour and multi-pass reconstituted flour:fine bran blend and for direct coarse grind WW flour and multi-pass reconstituted semolina:coarse bran blend. Semolna:fine bran or semolina:coarse bran blends made spaghetti with high cooked firmness, while spaghetti made from direct coarse grind or from semolina:fine bran or coarse bran blends had low cooking loss. Nineteen durum wheat (Triticum turgidum L. var. durum) cultivars and 17 breeding lines grown at 19 environments in North Dakota were evaluated for physical and cooking qualities of WW and traditional spaghetti. Of the 36 genotypes evaluated, 21 and 3 genotypes produced good and poor qualities of WW and traditional spaghettis, respectively, while other 12 genotypes produced good traditional spaghetti but produced poor quality WW spaghetti. These data indicate the need to select genotypes specifically for their WW pasta quality. Raw material traits (grain, semolina and WW flour characteristics) were evaluated to identify raw material traits iii capable of predicting WW spaghetti quality. Grain protein content had significant positive correlation with cooking quality of WW spaghetti. Stepwise multiple regressions showed grain protein content and mixogram break-time and wet gluten were the predominant characteristics in predicting cooking quality of WW spaghetti. iv ACKNOWLEDGMENTS Most sincere gratitude goes to my adviser Dr. Frank Manthey, who has given me invaluable advice, assistance, guidance and continuous encouragement during the pursue of my Ph.D degree. His support also helped me developed skills and abilities for my professional career. My appreciation extends to my other research committee members, Dr. Senay Simsek, Dr. Julie Garden-Robinson and Dr. Elias Elias. I highly appreciate their technical assistance and guidance for my research. My gratitude extends to Durum Wheat and Pasta Processing Lab technicians and students, Yu Liu, Hiroshi Ando, Jim Perleberg, Elena de la Peña and Claudia Cater, for their laboratory assistance and support. My special acknowledge expresses to Cereal Science Lipid Chemistry Lab, Dr. Clifford Hall and Mary Niehaus, for their laboratory assistance and technical support for part of my research study. My special acknowledge expresses to Cereal Science graduate students for their friendship and help. My great appreciation expresses to my family, Fayong Deng, Dongying Liao and Yizhong Deng, for their endless love and continuous support. v DEDICATION In memory of my uncle, Fahua Deng, your love and caring to the whole family are always remembered in my heart. vi TABLE OF CONTENTS ABSTRACT ................................................................................................................................... iii ACKNOWLEDGMENTS .............................................................................................................. v DEDICATION ............................................................................................................................... vi LIST OF TABLES ......................................................................................................................... xi LIST OF FIGURES ..................................................................................................................... xiii LIST OF APPENDIX TABLES ................................................................................................... xv GENERAL INTRODUCTION ....................................................................................................... 1 Literature Cited ........................................................................................................................... 3 CHAPTER 1: LITERATURE REVIEW ........................................................................................ 5 Durum Grain ............................................................................................................................... 5 Whole-Wheat Flour Milling ........................................................................................................ 6 Mill Techniques and Flour Quality – Single Pass ....................................................................... 7 Ultra-Centrifugal Mill.............................................................................................................. 7 Stone Mill ................................................................................................................................ 8 Hammer Mill ........................................................................................................................... 9 Disc Mill .................................................................................................................................. 9 Mill Techniques and Flour Quality – Multiple Pass ................................................................. 10 Roller Mill ............................................................................................................................. 10 Particle Size and Product Quality.............................................................................................. 10 Genotype and Pasta Quality ...................................................................................................... 11 Grain Traits for Milling Quality ................................................................................................ 12 Grain Traits for Pasta Quality ................................................................................................... 13 Protein Quantity ..................................................................................................................... 13 Protein Quality ....................................................................................................................... 14 vii Starch ..................................................................................................................................... 14 Sprouted Grain ....................................................................................................................... 15 Bran and Pasta Quality .............................................................................................................. 15 Color ...................................................................................................................................... 15 Mechanical Strength .............................................................................................................. 16 Cooking Quality .................................................................................................................... 16 Literature Cited ......................................................................................................................... 17 CHAPTER 2: LABORATORY-SCALE MILLING OF WHOLE-DURUM FLOUR QUALITY: EFFECT OF MILL CONFIGURATION AND SEED CONDITIONING .............. 26 Abstract ..................................................................................................................................... 26 Introduction ............................................................................................................................... 26 Materials and Methods .............................................................................................................. 28 Durum Wheat ........................................................................................................................ 28 Sample Preparation ................................................................................................................ 29 Mill Configuration ................................................................................................................