Effects of Serving Temperature on Sensory Perception and Acceptance of Brewed Coffee

Coffee continues to be one of the most widely consumed beverages worldwide. How an individual perceives a cup of coffee is impacted by a plethora of factors including origin, growing climate, roasting level, and consumption habits. This thesis utilized both trained descriptive panelists and untrained consumer panelists to analyze how serving/consumption temperature modulates sensory perception of brewed coffee in regards to appearance, aroma, flavor, taste, and mouthfeel. Three varieties of coffee (Colombia, Ethiopia, and Kenya) were brewed and served to panelists at four temperatures: 70, 55, 40, and 25 °C. In one study (Study 1, Chapter 3), results from descriptive analysis showed that product temperature had a larger effect in modulating sensory perception than did coffee variety. In another descriptive analysis study (Study 2, Chapter 3), trained panelists found that serving temperature had a more significant effect on perception than freshness, up to 90 minutes, of the brewed coffee sample of Ethiopian variety. Utilizing an untrained consumer panel and a Check-All-That-Apply (CATA) method to assess these same coffee samples, results showed that both serving temperature and coffee variety largely contributed to the variation in sensory perception. While these consumer panelists were more effective in differentiating between coffee varieties when assessing the samples at a lower (40 °C) temperature, liking of the sample was highest when served at hot temperatures (55 and 70 °C). This indicates that subtle attributes of brewed coffee may be easier to identify when served at lower temperatures. In a final study using CATA, additions of cream and sugar were added to the brewed coffee sample and served at four temperatures. Results showed that temperature is a significant modulator of sensory perception in enhanced coffee (i.e., brewed coffee with cream and/or sugar). The findings of this thesis show the importance of controlling temperature for the sensory evaluation of coffee products, since significant variations in both qualitative and quantitative sensory perception arise from changes in product temperature. © 2018 by Matthew J. Chapko All Rights Reserved Acknowledgements An abundance of thanks and appreciation goes out to Dr. Han-Seok Seo (Associate Professor, Department of Food Science) for his insight, patience, and support during this project as well as during his classes. Thank you to my committee members: Dr. Philip Crandall (Professor, Department of Food Science) and Dr. Andy Mauromoustakos (Professor, Agriculture Statistics Lab) for being available when needed and teaching me valuable skills while providing constant encouragement throughout both classes and the research process. I would also like to thank all of the other students and staff of the Sensory Service Center: Ms. Tonya Tokar (Former Lab Manager), Ms. Peggy Pang (Lab Technician), Ms. Tina McMaster (Lab Technician), Ms.Shilpa Samant (PhD student), Ms. Ragita Pramudya (Master student), Ms. Asmita Singh (Master student), and Ms. Samantha Varela (Lab Technician). I would also like to recognize Dr. Andy Bartlett (Clinical Assistant Professor, AFLS-AGST) for the lessons he gave me regarding statistics and coding. To my parents, Ed and Cindy Chapko, I give thanks and praise for being so helpful during my time in school and always being available for anything I needed. A final thank you is given to my wonderful wife, Rachel, who always believed in me and has given me a bright future to look