Read the full article on Nature.com

Because consumers expect their coffee to be hot, but not too hot, operators of coffeehouses, coffee shops, and cafés must make important decisions regarding the serving temperatures for their coffees. Clearly a key consideration is the preferred temperature range expected by consumers, but another important consideration is the risk of scald burns, which can cause tremendous injuries and occasionally result in high-profile litigation. Accordingly, several groups have investigated consumer preferences for coffee versus serving temperature. Borchgrevink et al. examined coffee at seven distinct temperatures evenly spaced between 57.2 and 90.6 °C and collected data on adequacy of serving temperature on a 5-point just-about-right (JAR) scale. They found that of those tested a serving temperature of 68.3 °C yielded an average numerical score closest to JAR. Pipatsattayanuwong et al. examined coffee served at six distinct temperatures over a broader range from 39.2 to 82.1 °C, using pairwise R-index values derived from ranking data, and found that 72.1 °C was the most preferred temperature of those tested. Lee and O’Mahony used a different approach by letting consumers freely mix hot and cold coffee until they obtained a preferred temperature. With this method, they found a much lower preferred temperature of 59.8 ± 8.1 °C, which they hypothesized was due to consumers adjusting the temperature to be suitable for drinking whole mouthfuls of coffee rather than smaller sips. Similar results were obtained more recently by Dirler et al., who also used a free-mixing method and found an average preferred temperature of 63 °C.

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Lead Author JIEXIN LIANG shares findings of a recent paper, “An Equilibrium Desorption Model for Strength and Extraction Yield of Full Immersion Brewed Coffee,” published in Scientific Reports, that outlines a predictive model for the equilibrium strength and extraction of “full immersion brewed coffee” (cupping) between 80°C and 99°C (176°F and 210°F) and suggests we’re more easily able to control our total dissolved solids (TDS) via brew ratio instead of our extraction yield (E).

Read the full article on SCA News and 25.

ANDREW COTTER considers the results of recent scientific publications focused on the impact of coffee’s brewing temperature on consumer preferences of brewed coffee.

Many of these variables—such as growth altitude, processing method, and roast level—can be controlled on a large scale by farmers and roasters in an effort to produce many bags of coffee that are nearly identical to one another. However, whole coffee beans in bags have not yet finished their process. Additional steps, such as grinding and brewing, are needed to make the final beverage that people will enjoy as their coffee. With these steps, a host of variables—that may influence the flavor of the brew and, in turn, how consumers like it—are in the hands of baristas and home brewers alike.

Read the full article on SCA News and 25.

Lead author Dr. MACKENZIE BATALI outlines findings from a recently published paper, “Titratable Acidity, Perceived Sourness, and Liking of Acidity in Drip Brewed Coffee,” that illuminate a key specialty coffee flavor attribute.

Beyond contributing either positively or negatively to the reception of the coffee, acidity is also mentioned as a component of other cupping score categories including flavor, balance, and defects; it likely contributes to uniformity and overall score as well.

Read the full academic paper in ACS Food Science and Technology

Acidity is a highly prized attribute in coffee, but there is little understanding of the brewing conditions under which acidity contributes favorable sensory attributes versus unfavorable sourness. Here, we examine the effect of titratable acidity and pH on the perception of sourness and consumer acceptance in drip brew coffee. Sour perception and acidity liking were assessed over a wide range of brew strengths and extraction yields at three different roast levels (light, medium, dark) and three different brewing temperatures (87 °C, 90 °C, and 93 °C). We find that perceived sour intensity correlates weakly with pH, but strongly with titratable acidity. Increases in titratable acidity also yielded increases in consumer perception of “too much acidity” and also impacted consumer liking and consumer preference segmentation with one cluster of consumers preferring more acidic coffee. Importantly, our data show that titratable acidity is linearly correlated with total dissolved solids (TDS) under all conditions studied, indicating that TDS is a good proxy for titratable acidity. The results presented here will provide the coffee industry with insight toward controlling perceived acidity or sourness, a key sensory attribute that substantially impacts consumer acceptance.

Read the full article on SCA News and 25.

Read the full article on SCA News and 25.

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?

Read the full article on SCA News and 25.

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?