Considerations for the Development and Optimization of Wine made from Partially Dehydrated Grapes in Ontario, Canada Jennifer Kelly, B.Sc., H.B.Sc. Centre for Biotechnology Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Faculty of Mathematics and Science, Brock University, St. Catharines, Ontario ©Jennifer M. Kelly, 2019 For my husband. Thank you for everything. ii Abstract The appassimento process for making wine can mitigate climatic challenges associated with cool climate winemaking, as fruit is dried post-harvest, reducing vintage-to-vintage variation due to varying fruit quality. Resultant wines fermented from dried grapes are high in ethanol and described as rich and intensely flavoured. One of the quality challenges facing wine made from partially dehydrated grapes is elevated levels of undesirable oxidation compounds, such as ethyl acetate, acetic acid and acetaldehyde. In this study we aim to characterize wines made from a local yeast isolate, Saccharomyces bayanus CN1, which demonstrates limited osmotolerance and may have application to this wine style, as it is a lower producer of such compounds. Wines made with the yeast of interest were compared to wines made with the accepted commercial yeast, Saccharomyces cerevisiae, EC1118. Fermentations were established over two vintages at one and three target starting sugar concentrations and a control, respectively. Wines were chemically (enzymatic) and sensorially analyzed. Wines (year two) were subject to volatile organic compound (VOC) and volatile fatty acid (VFA) measurements via Gas Chromatography-Mass Spectrometry. Another consideration for the development of this wine style is the inclusion of Botrytis cinerea, a pathogenic fungus that commonly develops during grape drying, and may impart favourable sensorial characteristics. Grapes were dried to 28.0°Brix and were fermented with EC1118 at 0 and 10% B. cinerea infection. A consumer preference test (n=153) that measured liking of wines (CN1 and 0% and iii 10% B. cinerea infection) was conducted. Results indicate that CN1’s upper limit for fermentation to dryness is 27.5°Brix. All CN1 wines had significantly lower concentrations (p<0.05) of oxidation compounds than the commercial yeast, and oppositely, higher glycerol levels, along with comparable ethanol concentration to EC1118 wines. Significant differences in the concentrations of VOCs and VFAs, such as 2-phenylethanol and hexanoic acid were observed both within °Brix treatments and amongst yeast strains. Sensorially, the wines differed in intensity for a number of attributes. The consumer study revealed no preference between wines vinified with the different yeast strains. This work will contribute to the optimization of this wine style in cool climate winemaking regions and beyond. iv Acknowledgements Thank you to our funding and granting agencies for your contribution to this project. Thank you to Pillitteri Estates Winery for your donation of grapes, and to Cave Spring Winery for use of your drying facility. I would like to take this opportunity to thank my supervisors, Drs. Debbie Inglis and Gary Pickering. Debbie, our meeting was meant to be. I am grateful to you for believing in me and encouraging me to be the best version of myself. You have truly made an impact on my life, and I am so lucky to have you as a supervisor. Gary, your encouragement and support and help with statistics and life in general has been invaluable to me. Thank you for always making time for me and making me feel valued. Thank you to my committee, Drs. Andy Reynolds Tony Yan for your suggestions and comments throughout my project and thesis. Thank you to my lab mates, past and present, who have been so helpful to me along the way. Caitlyn, Cristina, Tony, Esther, Leah, Margaret and Hannah, you have been good friends to me and I am so happy to have been on this journey with you. Fei, your guidance and support over the years has been immeasurable. Thank you. Lisa, I couldn’t have done this without you! You are a great winemaking partner. Shu-Fen, for always being a wealth of knowledge, thank you so much. To my dear friend and fellow Senator/marathoner, Andreanne- what would I do without you? Thank you. To Elena, Steve, Belinda and Barb- thank you for your kindness. To my sensory panelists, thank you for your dedication to this thesis. I appreciate your hard work so much! To all my friends, I swear I am alive. Stover, I am coming for you and that baby! To my brother and sister and Stephie and Maura, thank you for being the best encouragers I could ask for. And thank you for always sending me the jams to get me through the tough times! To my parents, I cannot thank you enough for your continued support. You have always believed this was possible even when I didn’t. This has been a long journey, and your cheerleading has never wavered. To my husband, you have made all of this possible for me. You really are the best. I am so lucky to have someone as supportive as you in my corner. Thank you. And finally, to the brightest light in my life, I would like to acknowledge the newest addition to my family; my son, Shandor. I love you more than you will ever know. v Table of Contents Abstract ........................................................................................................................... iii Acknowledgements .......................................................................................................... v List of Tables.................................................................................................................... ix List of Figures .................................................................................................................. xi Chapter 1 Literature Review ..................................................................................... 1 1. Introduction ............................................................................................................. 1 1.1 Wines made from Partially Dehydrated Grapes ......................................................... 9 1.1.1 History ............................................................................................................................ 10 1.1.2 Drying ............................................................................................................................. 11 1.1.3 Microbiota of Grape Surface During Drying ..................................................................... 17 1.2.2 Aroma and Flavour Composition ..................................................................................... 19 1.2 Fermentation Challenges for Wines made from Partially Dehydrated Grapes ......... 25 1.3 Yeast Selection for High Sugar Fermentation ........................................................... 30 1.4 Ontario Wine Industry .............................................................................................. 33 1.4.1 Cool Climate Winemaking ............................................................................................... 34 1.4.2 Regulations ..................................................................................................................... 35 1.4.3 CCOVI Appassimento Project .......................................................................................... 37 1.6 Literature Cited......................................................................................................... 39 Chapter 2 Characterization of Saccharomyces bayanus CN1 for Fermenting Partially Dehydrated Grapes Grown in Cool Climate Winemaking Regions .......................... 55 Abstract: ......................................................................................................................... 55 2.1 Introduction.............................................................................................................. 56 2.2 Materials and Methods ............................................................................................ 60 2.2.1 Yeast Strains ................................................................................................................... 60 2.2.2 Grape Harvest, Desiccation and Processing ..................................................................... 61 2.2.3 Winemaking ................................................................................................................... 62 2.2.4 Grape, Must and Fermentation Analysis .......................................................................... 64 2.2.5 Colour Evaluation ........................................................................................................... 65 2.2.6 Sensory Evaluation ......................................................................................................... 65 2.2.7 Statistical Analysis........................................................................................................... 66 2.2.8 Statement of Ethics......................................................................................................... 66 2.3 Results ...................................................................................................................... 66 2.3.1 Yeast Strain Identification ............................................................................................... 66 2.3.2 Fermentation Kinetics and Metabolites ........................................................................... 68 2.3.3 Colour and Sensory Evaluation: ......................................................................................