Starch and Antioxidant Properties of Quebec-bred Potato Genotypes Christina Larder Department of Plant Science Macdonald Campus of McGill University Montréal, Québec, Canada December 2015 A thesis submitted to McGill University in partial fulfillment of the requirements for the degree of Master of Science ©Christina Larder, 2015 I Table of Contents Abstract ........................................................................................................................................ VII Résumé ....................................................................................................................................... VIII Acknowledgements ........................................................................................................................ X Contribution of Authors ................................................................................................................ XI List of Tables ............................................................................................................................... XII List of Figures .............................................................................................................................. XV List of Abbreviations ................................................................................................................. XVI Chapter 1: General Introduction ..................................................................................................... 1 1.1 Introduction ........................................................................................................................... 1 1.2 Hypothesis ............................................................................................................................. 2 1.3 Objectives .............................................................................................................................. 3 1.4 Scope ..................................................................................................................................... 3 Chapter 2: Literature Review .......................................................................................................... 4 2.1 Starch Composition ............................................................................................................... 4 2.3 Resistant Starch ..................................................................................................................... 5 2.3.3 Factors Affecting Resistant Starch Digestibility ............................................................ 7 2.4 Measuring Starch................................................................................................................... 8 2.5 Phosphorylated Starch ........................................................................................................... 9 2.7 Glycemic Index and Glycemic Load ................................................................................... 10 2.8 Measuring Glycemic Index and Load Using an In Vitro Method....................................... 13 2.8 Health Concerns of Starch................................................................................................... 14 2.9 Use of Freeze-Dried Material for Starch Analysis .............................................................. 16 2.10 Protein Content .................................................................................................................. 17 2.11 Measuring Protein ............................................................................................................. 18 II 2.12 Ascorbic Acid, Phenolics, and Antioxidant Capacity ....................................................... 18 2.13 Measurement of Antioxidant Capacity and Polyphenols .................................................. 21 2.13.1 DPPH .......................................................................................................................... 21 2.13.2 ABTS .......................................................................................................................... 21 2.13.3 Folin-Ciocalteu ........................................................................................................... 22 2.13.4 HPLC .......................................................................................................................... 22 2.14 Starch Digestion, Antioxidants and Polyphenols .............................................................. 23 2.15 Hormesis............................................................................................................................ 24 2.16 Hormetic Trials with Potato .............................................................................................. 25 2.16.1 Hydrogen Peroxide as a Hormetic agent .................................................................... 25 2.16.2 Hydrogen Peroxide as a Hormetic Agent for Potatoes ............................................... 26 Connecting Statement ................................................................................................................... 32 Chapter 3: Phytonutrient Evaluation of Quebec Potato Genotypes .............................................. 33 3.1 Introduction ......................................................................................................................... 33 3.2 Materials and Methods ........................................................................................................ 35 3.2.1 Source Material ............................................................................................................. 35 3.2.2 Sample Preparation ....................................................................................................... 35 3.2.3 Percent Moisture ........................................................................................................... 36 3.2.4 Resistant, Digestible and Total Starch .......................................................................... 36 3.2.5 Isolation of Starch and Phosphorous Content............................................................... 37 3.2.6 Amylose Content .......................................................................................................... 38 3.2.7 In Vitro Digestibility of Starch, Predicted Glycemic Index and Load ......................... 39 3.2.8 Total Soluble Protein .................................................................................................... 40 3.2.9 Methanolic Crude Extracts ........................................................................................... 40 3.2.10 ABTS .......................................................................................................................... 41 III 3.2.11 DPPH .......................................................................................................................... 41 3.2.12 Folin-Ciocalteau ......................................................................................................... 41 3.2.13 Ascorbic Acid and Polyphenolic Profile .................................................................... 42 3.2.14 Statistical Analysis ..................................................................................................... 42 3.3 Results ................................................................................................................................. 43 3.3.1 Moisture Content .......................................................................................................... 43 3.3.2 Starch Profile ................................................................................................................ 43 3.3.3 Glycemic Index ............................................................................................................. 44 3.3.4 Glycemic Load ............................................................................................................. 45 3.3.3 Phosphorylated Starch .................................................................................................. 45 3.3.6 Amylose ........................................................................................................................ 45 3.3.7 Protein Content ............................................................................................................. 46 3.3.8 Antioxidant Capacity Tests .......................................................................................... 46 3.3. 9 Ascorbic Acid and Polyphenolic Profile Using HPLC ............................................... 48 3.3.11 Antioxidant and HPLC Correlations for Raw and Cooked Potato Samples .............. 49 3.3.12 Starch Correlations ..................................................................................................... 50 3.3.13 Predictive Models for GL ........................................................................................... 51 3.3.9 Discussion ........................................................................................................................ 52 Connecting Statement ................................................................................................................... 68 Chapter 4: Somaclone Starch Quality, Antioxidant Capacity, Ascorbic Acid, and Phenolic Profile Over Two Growing Seasons ......................................................................................................... 69 4.1 Introduction ........................................................................................................................