Flavor Chemistry and Gastronomy: Sensory, Instrumental, and Multivariate Approaches By ARIELLE JURCHAK JOHNSON B.S. (New York University) 2009 DISSERTATION Submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Agricultural and Environmental Chemistry in the OFFICE OF GRADUATE STUDIES of the UNIVERSITY OF CALIFORNIA DAVIS Approved: _________________________________ Susan E. Ebeler, Chair _________________________________ Hildegarde Heymann _________________________________ Roger B. Boulton Committee in Charge 2014 i Acknowledgements I would be remiss not to acknowledge the many people who have made this work possible, more or less chronologically: My parents, Martha Jurchak and Larry Johnson, for encouraging and pushing my intellectual, scientifc, and creative development from an early age; my brother and sister, Eban and Adriana Johnson; my Grandmother, Marie Jurchak, for planting the seed of bon vivantism and supplying the younger me with plenty of cookbooks to read; to my de-facto in-laws Alice Meadows and Pete, Grace, Jack and Joe Pold for welcoming me into their family. From the early days of what would turn out to be my career, Kent Kirshenbaum, for letting me stand in the back of the room at the frst Experimental Cuisine Collective meeting and giving me the space and support to start developing ideas about how to do scientifc research on culinary questions; and Dave Arnold for taking my half-developed ideas seriously and giving me a lot of challenging questions about smell and chemistry to fgure out. At UC Davis, my advisor, Susan Ebeler, for providing the tools and space to develop as an analytical chemist and learn the hard work of a writing, lecturing scientist, and putting up with my scientifc wanderings; Hildegarde Heymann, for teaching me everything I know about sensory science and experimental design, cultivating my ideas about how science should be dealing with questions of favor, chemistry, and cuisine, and freely ofering profound words of encouragement when I needed them. Carolyn Doyle, for invaluable instrumentation help. My lab and ofce mates, for their support and friendship, Larry Lerno, Helene Hopfer, Ellie King, Maya Hood White and especially Anna Hjelmeland, a stalwart friend both in and outside of work. Roger Boulton, for introducing me to the technology of distilled beverages and being a valuable and enjoyably challenging presence on both my qualifying exam and dissertation committees. Alyson Mitchell and Doug Adams for their presence on my qualifying exam committee and help with academic issues and conference travel. Harold McGee, frst as a role model, then as a QE committee member, and now as a dear friend and colleague. ii Related to the University of Copenhagen, Line Holler Mielby for being an early scientifc role model and encouraging me to go to Denmark, Michael Bom Frøst, for enabling my coming to the Nordic Food Lab and KU, my sensory panel at KU, and Wender Bredie, Belinda Nielsen, and Charlotte Dandanell of the sensory science group. My collaborators, all of which I thank primarily for giving me interesting and challenging questions (gastronomic and otherwise) to think about-Rene Redzepi for founding the Nordic Food Lab and welcoming me into the noma/mad family; David Chang for inviting me to explain olive phenolics Harvard; Rachel Dutton and Ben Wolfe; Josh Evans, Guillemette Barthouil, and Mark Emil Hermansen with their help making it happen at the Nordic Food Lab; Dan Felder; Rosio Sanchez for giving me interesting things about the psychological, cultural, and hedonic aspects of dessert to think about; Lars Williams, for taking my ideas and expertise seriously, teaching me how to throw a punch, and fundamentally changing the way I think about the production and development of knowledge and ideas. Paramount among the thanked is Tom Pold, the most encouraging, supportive, intellectually challenging, and wonderful signifcant other I think could possibly exist. Tank you for your patience, your vigilance, your encouragement, your love. I truly could never have done this without you. iii Contents Abstract 1 Chapter 1: Introduction and Literature Review 3 What is Flavor? 3 Smell and Chemistry 4 Analyzing Flavor 7 Analytical Flavor Chemistry 7 Descriptive Analysis and Sensometrics 11 Flavor and Multivariate Statistics 13 Principal Component Analysis 13 Partial Least Squares Regression 15 Multivariate Statistical Techniques on Non-Continuous or Nontraditional Data 16 Applied Flavor Chemistry: Science, Food, Culture 17 Flavor and chemistry of wine and other beverages 17 Cuisine Research and Development 19 References 27 Chapter 2: Perceptual Characterization and Analysis of Aroma Mixtures using In-Instrument Gas Chromatography Recombination-Olfactometry1 39 Abstract 39 Introduction 40 Materials and Methods 42 Instrument: 42 Sampling and Chromatographic Conditions 43 Sensory Conditions 44 Data Analysis 45 Results and Discussion 45 Conclusions 51 References 52 Acknowledgments 54 Supplementary Information: 55 Chapter 3: Volatile and Sensory Profling of Cocktail Bitters 59 Introduction 59 Materials & Methods 64 Samples 64 Chemical Analysis 64 Sensory Analysis 65 Statistical Analysis 67 Results & Discussion 67 Sensory Analysis 67 Gas Chromatography-Mass Spectrometry 70 Flavor Chemistry of Bitters 77 Conclusions 85 References 87 Chapter 4: GC-Recomposition-Olfactometry (GRO) and multivariate study of three terpenoid compounds in the aroma profle of Angostura bitters 96 iv Introduction 96 Materials and Methods 99 Bitters: 99 Sample Preparation and Extraction: 99 Instrument and Conditions: 100 Sensory Conditions: 101 Statistical Analysis: 101 Results and Discussion: 102 References 110 Chapter 5: Aroma Perception and Chemistry of Bitters in Whiskey Matrices: Modeling the Old- Fashioned Cocktail 113 Introduction 113 Materials and Methods 114 Whiskey: 114 Bitters: 114 Model Old-Fashioned: 114 Sensory Analysis: 116 GC-MS: 117 Analysis of Variance: 118 Means and Signifcant Diferences: 118 Principal Component Analysis (PCA): 118 Partial Least Squares Regression (PLS): 122 Results and Discussion: 122 References 132 Chapter 6: Sensory Attributes and Flavor Chemistry of Acetic Fermentations with Novel Plant Ingredients 136 Introduction 136 Materials and Methods 137 Acetifcation: 137 Juice Vinegars: 138 Tea Vinegars: 138 Wine Vinegars: 139 Sensory Analysis: 139 Volatile Analysis: 140 Chromatographic Conditions: 140 Compound Identifcation and Relative Quantifcation: 142 Capillary Electrophoresis: 142 Statistical Analysis: 142 Results and Discussion 143 Sensory Analysis: 143 Chemical Analysis: 146 PLS 152 References 159 Chapter 7: Correlating Labeled Sorting Sensory Analysis and Volatile Analysis of Malt Vinegars with Novel Ingredients 165 v Introduction: 165 Materials and Methods: 167 Vinegar Production 167 a. Base Beer Fermentation: 168 b. Acetifcation and favoring: 169 Sensory Analysis: 169 GC-MS: 169 Statistical Analysis: 170 a. Sorting: 170 b. Labels: 171 c. Volatiles: 171 d. Multiple Factor Analysis (MFA): 171 Results and Discussion: 171 References 186 Conclusions 191 vi List of Tables and Figures Figure 2.1 Conceptual schematic of the In-Instrument Gas Chromatograph Recombination Olfactometer (GRO) instrument. Volatiles are extracted onto a solid phase (via solid-phase microextraction or SPME) from the headspace of a food, beverage, or other sample, in this case, lavender fowers, and initially they are separated conventionally on an analytical capillary GC column. In-line with the GC column, a pneumatic Deans Switch followed by a cold trap allows the experimenter to build a mixture of these separated volatiles that is held until the cryotrap is rapidly heated, releasing the mixture for a subject to smell at the olfactory port and evaluate. 41 Figure 2.2 Schematic of (a) standard GC-MS; (b) GC-MS with splitter at end of column for olfactometry; and (c) In-instrument Gas chromatograph- Recombination Olfactometer or GRO with Deans switch, splitter, cryogenic trap and olfactory port. Abbreviations: i-inlet; c-column; d-detector; o-oven; olf-olfactometry port; sp-splitter; sw-Deans switch 1; w-waste; cr-cryogenic trap; and cb-switch 2 on control box. 42 Table 2.1 Experimental GC-O conditions and aroma descriptors for mixtures of volatiles from the lavender chromatograms. 43 Figure 2.3 Top aroma descriptors for mixtures of sections of the lavender chromatogram by cut time and chromatogram composition. Abbreviations correspond to Experimental Conditions described in Table 1. As chemical complexity and number of components per mixture approaches the makeup of the whole chromatogram (W) mixture, there is evidence of perceptual additivity as increasing cross-utilization of terms from simpler mixtures, masking as reduced use of dominant terms for simpler (P1-P6) mixtures, and synergistic efects as new complex or composite terms like “fresh lavender” become important. 45 Figure 2.4 Correspondence Analysis of (A) lavender volatile mixtures; and (B) lavender volatile mixture descriptors. Abbreviations for mixtures correspond to those in Table 1. Terms generated by the panelists to describe the perceived odor of from each Experimental Condition described in Table 1 were tabulated by frequency of use and used for the Correspondence Analysis. 30.57% of variance explained by dimension 1 (x), 22.84% of variance explained by dimension 2 (y). 46 Figure 2.5 Te rated representativeness of the aroma of samples W, O1-O3, and P1-P6 as compared by panelists to the aroma of whole fowering