Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 2003 Role of starch structure in texture of winter squash (Cucurbita maxima D) fruit and starch functional properties David Graham Stevenson 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 Stevenson, David Graham, "Role of starch structure in texture of winter squash (Cucurbita maxima D) fruit and starch functional properties " (2003). Retrospective Theses and Dissertations. 1465. https://lib.dr.iastate.edu/rtd/1465 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. For more information, please contact [email protected]. Role of starch structure in texture of winter squash (Cucurbita maxima D.) fruit and starch functional properties by David Graham Stevenson A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Food Science and Technology Program of Study Committee: Jay-lin Jane, Major Professor Pamela White Jane Love John Robyt Ted Bailey Iowa State University Ames, Iowa 2003 UMI Number: 3105108 UMI UMI Microform 3105108 Copyright 2003 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 ii Graduate College Iowa State University This is to certify that the Doctoral dissertation of David Stevenson has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Com itt e Member Signature was redacted for privacy. Committe Member Signature was redacted for privacy. Con iittee Member Signature was redacted for privacy. Committee Member Signature was redacted for privacy. Major Prof sor Signature was redacted for privacy. For the Major Program Signature was redacted for privacy. For the Graduate Coll e iii TABLE OF CONTENTS GENERAL INTRODUCTION 1 Introduction 1 Dissertation Organization 3 LITERATURE REVIEW 5 Starch Structural Properties 5 Amylopectin Structure 5 Amylose Structure 14 Starch Granule 26 Phosphorus Content 41 Starch Functional Properties 44 Starch Gelatinization 44 Starch Rétrogradation 53 Pasting Properties 56 Fruit Starches 61 Squash Fruit Starches 62 Food Texture Measurements 63 Texture Profile Analysis 63 Texture of Squash Fruit 64 Role of Starch in Texture of Squash Fruit 65 Squash Texture and Cell Wall Polysaccharides 66 Starch Content and Texture 67 Amylose and Texture 70 Amylopectin and Texture 72 Starch Thermal Properties and Texture 74 Starch Pasting Properties and Texture 75 Amylose Effect on Pasting Properties 76 Amylose Effect on Thermal Properties 77 Amylopectin Effect on Pasting Properties 78 Amylopectin Effect on Thermal Properties 78 Relationship Between Starch Thermal and Pasting Properties 79 Ultrasound as Tool for Texture Measurements 80 Ultrasound in Food Science 80 Ultrasonics for Evaluation of Fruits and Vegetables 81 References 83 CHAPTER 1. STRUCTURAL AND PHYSICOCHEMICAL CHARACTERISTICS OF WINTER SQUASH (Cucurbita maxima D.) FRUIT STARCHES AT HARVEST 127 ABSTRACT 127 INTRODUCTION 128 MATERIALS AND METHODS 129 RESULTS AND DISCUSSION 134 CONCLUSION 146 IV ACKNOWLEDGEMENTS 146 REFERENCES 146 CHAPTER 2. ROLE OF STARCH STRUCTURE IN TEXTURE OF SQUASH AND STARCH FUNCTIONAL PROPERTIES. I. STRUCTURAL PROPERTIES OF STARCH EXTRACTED FROM WINTER SQUASH FRUIT 0Cucurbita maxima D.) AT HARVEST AND AFTER STORAGE. 170 ABSTRACT 170 INTRODUCTION 171 MATERIALS AND METHODS 172 RESULTS AND DISCUSSION 177 ACKNOWLEDGMENT 186 LITERATRUE CITED 186 CHAPTER 3. ROLE OF STARCH STRUCTURE IN TEXTURE OF SQUASH AND STARCH FUNCTIONAL PROPERTIES. II. FUNCTIONAL PROPERTIES OF STARCH EXTRACTED FROM WINTER SQUASH FRUIT (Cucurbita maxima D.) AT HARVEST AND AFTER STORAGE 213 ABSTRACT 213 INTRODUCTION 214 MATERIALS AND METHODS 215 RESULTS AND DISCUSSION 217 ACKNOWLEDGMENT 223 LITERATURE CITED 224 CHAPTER 4. ROLE OF STARCH STRUCTURE IN TEXTURE OF SQUASH AND STARCH FUNCTIONAL PROPERTIES. III. TEXTURE OF RAW AND COOKED WINTER SQUASH (<Cucurbita maxima D.) FROM FRUIT AT HARVEST AND AFTER STORAGE 238 ABSTRACT 238 INTRODUCTION 239 MATERIALS AND METHODS 240 RESULTS AND DISCUSSION 242 ACKNOWLEDGEMENT 252 LITERATURE CITED 252 CHAPTER 5. ROLE OF STARCH STRUCTURE IN TEXTURE OF SQUASH AND STARCH FUNCTIONAL PROPERTIES. IV. CORRELATIONS AMONG STARCH STRUCTURE, STARCH FUNCTIONALITY AND TEXTURE OF WINTER SQUASH (Cucurbita maxima D.) FROM FRUIT AT HARVEST AND AFTER STORAGE 263 ABSTRACT 263 INTRODUCTION 264 MATERIALS AND METHODS 266 V RESULTS AND DISCUSSION 268 CONCLUSION 292 ACKNOWLEDGMENT 292 LITERATURE CITED 293 CHAPTER 6. ROLE OF STARCH STRUCTURE IN TEXTURE OF SQUASH AND STARCH FUNCTIONAL PROPERTIES. V. TRANSMISSION OF ULTRASOUND AND MICROSCOPIC OBSERVATIONS PF WINTER SQUASH (Cucurbita maxima D.) FRUIT TO EXAMINE TEXTURE AND CORRELATIONS WITH STARCH AND CELL WALLS 319 ABSTRACT 319 INTRODUCTION 320 MATERILAS AND METHODS 322 RESULTS AND DISCUSSION 327 CONCLUSION 324 ACKNOWLEDGMENT 324 LITERATURE CITED 325 CHAPTER 7. SEASONAL VARIATION IN WINTER SQUASH (<Cucurbita maxima D.) FRUIT. I. VARIATION IN STARCH STRUCTURAL AND FUNCTIONAL PROPERTIES 353 ABSTRACT 353 INTRODUCTION 354 MATERIALS AND METHODS 355 RESULTS AND DISCUSSION 358 ACKNOWLEDGEMENTS 367 REFERENCES 367 CHAPTER 8. SEASONAL VARIATION IN WINTER SQUASH (Cucurbita maxima D.) FRUIT. II. VARIATION IN TEXTURE OF RAW AND COOKED FRUIT 384 ABSTRACT 384 INTRODUCTION 385 MATERIALS AND METHODS 386 RESULTS AND DISCUSSION 387 ACKNOWLEDGEMENTS 394 REFERENCES 394 CHAPTER 9. VARIATION IN AGRONOMIC TRAITS, STARCH STRUCTURAL PROPERTIES, STARCH FUNCTIONAL PROPERTIES AND TEXTURAL ATTRIBUTES OF Cucurbita maxima D. cv. Zapallo Macre WINTER SQUASH FRUIT 403 ABSTRACT 403 INTRODUCTION 404 EXPERIMENTAL 404 vi RESULTS 410 DISCUSSION AND CONCLUSIONS 416 ACKNOWLEDGEMENTS 418 REFERENCES 418 CHAPTER 10. STRUCTURAL AND FUNCTIONAL PROPERTIES OF APPLE (Malus domestica Borkh) FRUIT STARCH 437 ABSTRACT 437 INTRODUCTION 437 MATERIALS AND METHODS 439 RESULTS AND DISCUSSION 444 CONCLUSION 456 ACKNOWLEDGMENT 456 REFERENCES 456 GENERAL CONCLUSIONS 476 APPENDIX A - SQUASH FRUIT AND OTHER PICTURES OF CULTIVATION 483 APPENDIX B - INSTRON UNIVERSAL TESTING MACHINE MEASUREMENTS OF TEXTURE 496 APPENDIX C - APPLE CULTIVARS SELECTED FOR STARCH STUDY 498 APPENDIX D - WHY ARE JACK-O-LANTERN PUMPKINS USED FOR HALLOWEEN CARVING? 502 ACKNOWLEDGEMENTS 503 vii ABSTRACT Starch structural and functional properties of 13 winter squash (Cucurbita maxima D.) cultivars were investigated at harvest and after 5 or 10 weeks storage at 12°C. Texture profile analysis was carried out on winter squash fruit steamed at 6 different cooking times from 0 to 20 minutes, and for all three storage times. Buttercup squash cultivars had very high proportion of dry matter as starch (50-60%), whereas Halloween squash often accumulate no starch. Squash starches were B-type, with long amylopectin branch chain- lengths, low amylopectin polydispersity, gelatinization temperature of 60-65°C, and narrow range of gelatinization temperatures. Starch pastes had high peak and final viscosity, and high setback. Hardness of fruit was similar after 10 weeks storage, fracturability increased during storage and springiness of squash fruit decreased during storage. Correlations among squash starch structural and functional properties, and fruit textural attributes were observed. Starch content was positively correlated to fruit hardness and fracturability when raw and negatively correlated at long-duration cooking times. Springiness of raw and cooked fruit was negatively correlated to starch content. Apparent amylose content correlated negatively to hardness and fracturability of squash fruit, but absolute amylose content correlated positively to hardness and fracturability. Hardness and fracturability of squash fruit was consistently correlated to short (DP < 12) and long (DP >37) amylopectin branch chain- lengths and negatively correlated to intermediate amylopectin branch chain-lengths (DP 13- 36), regardless of storage time. Starch structural and functional properties, and textural attributes all varied among seasons. Ultrasound was transmitted through raw and cooked squash fruit as novel method of measuring texture. Ultrasonic velocity (UV) was slower than air for raw fruit, and despite softening during cooking, UV increased as squash were steamed. Light microscopy analysis showed fruit with fastest UV had cells engorged with gelatinized starch, whereas fruit with slower UV had no starch or other material in their cells. Zapallo fruit had dramatic variation in starch accumulation and could be used as model system for starch biosynthesis. Apple starches were also studied and were C-type with long amylopectin branch chains and low paste breakdown. 1 GENERAL INTRODUCTION Introduction Starch is debatably the most abundant carbohydrate on Earth. Starch is abundant in leaves and stems of green plants, and their associated storage organs such as roots, tubers, fruits and seeds. Starch serves as the chemical energy from sunlight energy during photosynthesis. Starch is