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Consumer Preferences for Black Coffee are Impacted by Extraction

出版	University of California, Davis, 2020
ISBN	9798691213458
URL	http://books.google.com.hk/books?id=LCqAzwEACAAJ&hl=&source=gbs_api

註釋Background: The Coffee Brewing Control Chart (BCC) is a tool that is commonly used throughout the coffee industry to assess the performance of baristas and automatic brewers, using easily measurable extraction-related variables to predict the flavor and acceptability of the resulting beverage. It relates the total dissolved solids (TDS) content of the beverage to the "strength" of the brew and the extraction yield (percent extraction, PE) to the balance of flavors using terms such as "underdeveloped" to describe low PE and "bitter" to describe high PE. In the middle of this chart lies an "ideal" region that is meant to deliver the best flavor intensity and flavor balance, and the extraction profile highlighted by this region is endorsed by the Specialty Coffee Association (SCA) and recognized as the "Gold Cup Standard." Objectives: The goal of this research was to expand upon the BCC using modern sensory analysis and statistical methodologies that were not available at the time of the inception of the original version. We investigated the nine regions highlighted by the BCC at three different brewing temperatures (BT) for changes in flavor profile and acceptability. This research specifically probed the use of the term "ideal" to describe the extraction profile that lies at the center of the chart, and we investigated whether this was a true ideal for a sample of black coffee drinkers in Northern California. Methods: Preliminary data focused on the effect of brewing temperature alone was collected by having one hundred and eighty-nine coffee consumers perform a two-alternative forced choice task on coffees brewed at different temperatures (87°C and 93°C). A more exhaustive study had one hundred and eighteen mostly college-age, self-reported consumers of black coffee taste coffees that varied in BT, TDS and PE. For each coffee, consumers rated overall acceptance on the 9-point hedonic scale; the adequacy of serving temperature, flavor intensity, acidity and mouthfeel using 5-point just-about-right (JAR) scales; described the flavor using a check-all-that-apply (CATA) list of 17 attributes; and rated purchase intent using a 5-point scale. A descriptive analysis study was run concurrent with the consumer study using the same coffee and the same experimental design, and the results of that study will be cited throughout this thesis. Results: The preliminary study found no significant preference (p>0.05) for the coffees based on brewing temperature alone. The results of the second study found substantial variation in consumer preferences, and that differences between individual preferences were most heavily influenced by TDS. Consumer preference clustering was performed, and two preference segments were investigated. Their ideal extraction profiles were defined using response surface methodology (RSM), and drivers of liking/disliking were identified using external preference mapping (EPM) and penalty analysis. Perceived acidity, overall flavor intensity and mouthfeel were found to be important attributes that drove the difference in preferences for the two identified consumer segments. Conclusions: The data presented here will aid in the development of a new BCC that better describes the flavor changes and changes in acceptability that result from changes in TDS and brewing time rather than PE. The acceptability component of this new chart should consider the variation in preferences that result from changes in TDS and highlight the areas of maximum liking for the different preference clusters that exist in a variety of different consumer populations.