Impact of Beverage Temperature on Consumer Preferences for Black Coffee
Researchers William D. Ristenpart, Andrew R. Cotter, and Jean-Xavier Guinard of the UC Davis Coffee Center published an open-access research article in Scientific Reports (2022), reporting results from CSF-funded research into consumer preferences for the temperature of black coffee.
Drawing on more than 3,000 tastings, they identified the temperature range most consumers find acceptable and the minimum first-sip temperature at which almost nobody finds the coffee too cold. They also compared how much temperature affected liking relative to other attributes such as flavor intensity and acidity.
The scientific findings are useful for anyone setting brewing, holding, and serving practices in cafés.
Read the full article on nature.com
How Strong is the Coffee You’re Cupping? New Model Captures the Equilibrium Extraction Nature of Full Immersion Brewing
Jiexin Liang, Ka Chun Chan, and Professor William D. Ristenpart of the UC Davis Coffee Center share findings from CSF-funded research into full-immersion brewing in the SCA journal 25.
Their 2022 article presents a model that predicts how strong a full-immersion brew will be once it settles (its equilibrium strength) and how much of the coffee dissolves. The researchers tested the model in 99 experiments plus cupping trials across several roast levels.
The findings are useful for cuppers and anyone brewing by immersion, such as with a French press, siphon, or cold brew.
Access the article free with an SCA Portal account (choose Associate Member).
How Hot is Hot Enough? Brew Temperature, Sensory Profile, and Consumer Acceptance of Brewed Coffee
Andrew R. Cotter of the UC Davis Coffee Center summarizes CSF-funded research into consumer preferences for black brewed coffee in a plain-language article for 25 (issue 15, 2021). The research asked whether brew temperature itself changes how coffee tastes or whether it matters because it affects strength (TDS) and extraction.
A trained panel and a group of 118 consumers tasted one coffee brewed 27 different ways, and the researchers analyzed their assessments to see how strength, extraction, and brew temperature interacted and affected flavor and liking.
The findings are useful to anyone creating recipes for brewed coffee. Access the article free with an SCA Portal account (choose Associate Member).
Manipulating and Measuring a Key Attribute in Drip Brew Coffee
Dr. Mackenzie Batali summarizes CSF-funded research into acidity in black drip coffee in a plain-language article for 25 (issue 15, 2021). The research investigated whether pH level and titratable acidity can predict perceived sourness. The researchers also tracked how brew strength (TDS) and extraction affect these measurements and perceived sourness.
The article is useful for roasters, baristas, and quality-control teams who want a practical way to measure and adjust acidity, and for cafés serving customers who have different preferences around acidity.
Access the article free with an SCA Portal account (choose Associate Member).
Titratable Acidity, Perceived Sourness, and Liking of Acidity in Drip Brewed Coffee
Dr. Mackenzie Batali, Andrew R. Cotter, Dr. Scott C. Frost, Professor William D. Ristenpart, and Professor Jean-Xavier Guinard of the UC Davis Coffee Center published a peer-reviewed research article in ACS Food Science & Technology (2021), reporting CSF-funded research into acidity in black drip coffee. The research investigated whether pH and titratable acidity can predict perceived sourness and consumer liking across a wide range of brew strengths and extraction yields, three roast levels, and three brew temperatures.
The article is useful for roasters, baristas, and quality-control teams who want to measure and control acidity, and for cafés serving customers who have different preferences around acidity.
An equilibrium desorption model for the strength and extraction yield of full immersion brewed coffee
Jiexin Liang, Ka Chun Chan, and Professor William D. Ristenpart of UC Davis published an open-access research article in Scientific Reports (March 2021), reporting research funded by the CSF. The research built a model to predict the TDS and extraction yield of a brew once it reaches equilibrium strength. The researchers tested the predictive model against lab brews and traditional cupping.
This article is useful for cuppers and brewers who want to gain a thorough scientific understanding of full-immersion brewing.
Read the full academic publication in Scientific Reports.
Consumer Preferences for Black Coffee are Spread Over a Wide Range of Brew Strengths and Extraction Yields
Andrew R. Cotter, Dr. Mackenzie Batali, Professor William D. Ristenpart, and Professor Jean-Xavier Guinard of the UC Davis Coffee Center published a peer-reviewed research article in the Journal of Food Science (2021). They studied how TDS, extraction yield, and brew temperature affected consumer preference. Using preference-mapping techniques, they identified clusters of consumers with varying preferences and suggested that the Coffee Brewing Control Chart should be updated to reflect consumer preference segmentation.
The article is valuable for those wanting to adjust brewing styles to suit consumer preferences, as well as for trainers.
Towards a New Brewing Chart
Dr. Scott Frost, Mackenzie Batali, Professor Jean-Xavier Guinard, and Professor William D. Ristenpart of the UC Davis Coffee Center summarize CSF-funded research toward an updated Coffee Brewing Control Chart in a plain-language article for 25 (issue 13). The research asked how flavor changes with brew strength (TDS) and extraction, going beyond the classic chart’s few broad labels, such as “bitter” and “underdeveloped.”
The article is useful for baristas, trainers, café owners, and anyone who manipulates brew recipes to achieve flavor outcomes or match consumer preferences.
Access the article free with an SCA Portal account (choose Associate Member).
Brew Temperature, at Fixed Brew Strength and Extraction, has Little Impact on the Sensory Profile of Drip Brew Coffee
Dr. Mackenzie E. Batali, Professor William D. Ristenpart, and Professor Jean-Xavier Guinard of UC Davis published an open-access research article in Scientific Reports (October 2020), reporting SCA-funded research into how brew temperature affects the flavor of black drip coffee. The research investigated the presumption of an “optimal brew temperature” and tested whether brewing water temperature changed how coffee tastes on its own or only because it affected strength (TDS) and extraction.
The article is useful for baristas, World Coffee Competitions competitors, café operators, and brewer manufacturers, as it helps to establish how relevant brew temperature is to sensory outcomes.
Effects of brew strength, brew yield, and roast on the sensory quality of drip brewed coffee
Dr. Scott C. Frost, Professor William D. Ristenpart, and Professor Jean-Xavier Guinard of the UC Davis Coffee Center published a peer-reviewed research article in the Journal of Food Science (2020), reporting CSF-funded research into the flavor of black drip coffee. The research investigated how brew strength (TDS) and extraction affect coffee’s flavor, going beyond the classic Coffee Brewing Control Chart’s broad labels, such as “bitter” and “underdeveloped.”
The results provide new insight into how to optimize brewing conditions to achieve desired sensory profiles in drip-brewed coffee.
The article is useful to trainers or brewers wanting to develop a scientific understanding of brew variables and sensory profiles. Read the full academic paper in Journal of Food Science.
Sensory and Monosaccharide Analysis of Drip Brew Coffee Fractions Versus Brewing Time
Read the full academic paper in Journal of the Science of Food and Agriculture
The composition of drip brew coffee versus brewing time has been chemically characterized in previous studies, and it is known that the total dissolved solids (TDS) systematically decreases with each fraction during the brew. Little information exists regarding the corresponding sensory attributes versus time, however, and it is unclear how TDS correlates with flavor profile.
The results of the sensory analysis and the monosaccharide analysis suggest that perceptible sweetness in coffee is a consequence of masking effects and/or the presence of sweet‐associated aromas and flavors. The results further suggest that unique flavor profiles could be obtained from the same coffee grounds by judicious combinations of specific fractions. © 2020 Society of Chemical Industry
Less Strong, More Sweet
Read the full article on the SCA Portal.
Graduate student MACKENZIE BATALI, Professor CARLITO LEBRILLA, Professor JEAN-XAVIER GUINARD, and Professor WILLIAM D. RISTENPART share surprising results of “fractionation” experiments at UC Davis exploring the natural sweetness of black drip brew coffee in partnership with the SCA and Breville Corporation.
If you talk to aficionados of specialty coffee, however, you quickly learn that other sensory attributes are paramount. In fact, a word you are likely to hear from coffee experts, often uttered in reverential tones, is sweetness.
Typical consumers associate sweetness in coffee with the act of stirring in sugar or artificial sweetener, but that’s not what we’re talking about here. Rather, coffee experts have long known that black coffee, without any additives, can have perceptible sweetness. Considered by many to be the holy grail of specialty coffee, natural sweetness is a sublime pleasure for those who get to enjoy it in the cup. At the same time, however, natural sweetness can be maddening to those who need to make it happen. Anybody who sources, roasts, or brews coffee professionally knows that delivering natural sweetness in black coffee isn’t easy: sweetness is fleeting, fluctuating from lot to lot of beans or in response to minor differences in roast or brew conditions. This difficulty raises an important question: How do you maximize the natural sweetness in black coffee?
Effect of Basket Geometry on the Sensory Quality and Consumer Acceptance of Drip Brewed Coffee
Read the full academic paper in Journal of Food Science
In this work, discrimination tests, descriptive analysis, consumer tests, and total dissolved solids (TDS) were used to evaluate the effects of brew basket geometry on the sensory quality and consumer acceptance of drip brewed coffee. Semi‐conical and flat‐bottom brewing shapes were evaluated in conjunction with coffee roast and particle size. This research found that attributes showing significant interactions with brewing geometry were also key drivers of consumer liking/disliking. Overall consumer liking was analyzed by cluster analysis, which revealed four distinct preference clusters. For each cluster, a particular basket geometry and/or roast level showed lesser acceptance, further confirming the hypothesis that basket geometry affects the sensory quality of drip-brewed coffee.
Flat vs. Cone: Basket Shape is as Important as Grind Size in Drip Brew Coffee
Read the full article on the SCA Portal.
One of the most reliable ways of starting a passionate argument, at least in a room filled with coffee aficionados, is to ask a simple question: What is the best shape for a drip brew filter basket?