Read the full article on the SCA Portal.

Lead author SARA YEAGER shares the findings of a recently published paper, “Roast Level and Brew Temperature Significantly Affect the Color of Brewed Coffee,” published in the Journal of Food Science, exploring how coffee beverage color varies with origin, roast level, and brew temperature.

Watch the discussion on the SCA Youtube channel.

Part of an ongoing body of research from the UC Davis Coffee Center, this lecture will explore how temperature, at a fixed total dissolved solids and percent extraction, impacts the quality of drip brew coffee as assessed by an expert panel. In addition, we discuss how the work serves a broader goal to expand and update the classic Coffee Brewing Control Chart with more detailed sensory language, and how we can use these results to brew better coffee.

Presented By: Mackenzie Batali, Graduate Student Researcher, University of California, Davis

Watch the discussion on the SCA Youtube channel.

Part of an ongoing body of research from the UC Davis Coffee Center, this lecture will explore how temperature, at a fixed total dissolved solids and percent extraction, impacts the quality of drip brew coffee as assessed by an expert panel. In addition, we discuss how the work serves a broader goal to expand and update the classic Coffee Brewing Control Chart with more detailed sensory language, and how we can use these results to brew better coffee.

Presented By: Mackenzie Batali, Graduate Student Researcher, University of California, Davis

Read the full article on the SCA Portal.

Lead author Dr. MACKENZIE BATALI shares the results of a controlled and systematic study exploring the impact of the cold brew process on the sensory profile of the beverage it produces, recently published in MDPI’s open access journal, Foods.

Read the full article on the SCA Portal.

The SCA’s Content Development Manager, Laurel Carmichael, speaks to researchers at the Hendon Coffee Lab about their chemistry lab that looks like a café, and about how they use electrochemistry and Design of Experiments to better understand the complexities of espresso extraction.

Read the full academic publication.

The process of grinding coffee generates particles with high levels of electrostatic charge, causing a number of detrimental effects including clumping, particle dispersal, and spark discharge. At the brewing level, electrostatic aggregation between particles affects liquid-solid accessibility, leading to variable extraction quality. In this study, we quantify the effectiveness of four charge mitigation strategies. Our data suggests that adding small amounts of water to whole beans pre-grinding, or bombarding the grounds with ions produced from a high-voltage ionizer, are capable of de-electrifying the granular flows. While these techniques helped reduce visible mess, only the static reduction through water inclusion was found to impact the brewing parameters in espresso format coffee. There, wetting coffee with less than 0.05 mL / g resulted in a marked shift in particle size distribution, in part due to preventing clump formation and also liberating fine particles from sticking to the grinder. With all other variables kept constant, this shift resulted in at least 15% higher coffee concentration for espresso extracts prepared from darker roasts. These findings pose financial and sustainability implications, and encourage the widespread implementation of water use to de-electrify coffee during grinding.

Watch a lecture from Re:co, the Specialty Coffee Symposium, 2023 by Prof. Christopher H. Hendon.

As technology advances and our understanding of sensory attributes improves, it's possible to put more power in the hands of coffee professionals who seek to make coffee better. Get the latest update about this multi-year research project aimed at measuring espresso chemistry, correlating those measurements to sensory attributes, and laying the groundwork for science-based useable tools for the coffee industry.

Read the full article on the SCA Portal.

Dr. JOSHUA MÉNDEZ HARPER and Dr. CHRISTOPHER H. HENDON discuss the chemistry and physics behind the electrification of coffee during grinding, its effect on extraction, and strategies to mitigate it. All images are adapted from their recent academic publication “Moisture-Controlled Triboelectrification During Coffee Grinding,” published in Matter.

Read the full academic publication.

Despite coffee's popularity, there are no quantitative methods to measure a chemical property of a black coffee drink in situ and relate it to a flavor experience. Here we show that cyclic voltammetry can be used in coffee without any additional sample preparation to directly measure the strength of a coffee beverage and, separately, how dark the coffee has been roasted; these two properties are implicated in the sensory profile of the beverage. We show that the current passed for the cathodic features that precede hydrogen evolution are linearly related to beverage strength. The same features are suppressed with subsequent cycling, and we show that the magnitude of suppression is directly related to roast color, which dictates the ensemble chemical composition and thus flavor of the beverage. Together, this voltametric analysis decouples beverage strength from roast color and offers a new strategy for rapidly assessing chemical properties of coffee that correlate to flavor.

Read the full article on the SCA Portal.

The SCA’s Publications Manager, LAUREL CARMICHAEL, introduces a Coffee Science Foundation research project on the sensory impact of physical defects in green coffee, undertaken at the Coffee Excellence Center at the Zurich University of Applied Sciences.

Watch the lecture on the SCA Youtube channel.

DR. NANCY CORDOBA speaks on research into coffee sweetness at Re:co Symposium.

Specialty coffee consumers and experts alike agree that a key part of coffee quality is the natural sweetness that is a part of high-quality coffee flavor. Recent research has confirmed that, counterintuitively, the sweetness in coffee does not come from sugars in the bean. This has created something of a mystery among coffee experts and sensory scientists —if sugars do not make coffee taste sweet, what could be the reason for the sweet taste of high-quality coffee?

Natural sweetness makes coffee more valuable to consumers, roasters, and coffee farmers alike, which is why it is being recognized as a sensorial evaluation category within the SCA’s Coffee Value Assessment System. Solving the mystery of sweetness, then, is a key element of the SCA's journey to make coffee better and more sustainable.

Read the full article on the SCA Portal.

Researchers Dr. NANCY CORDOBA and Dr. DEVIN PETERSON, joined by PETER GIULIANO, share early results of a multi-year Coffee Science Foundation research project, undertaken at the Flavor Research and Education Center at Ohio State University, to establish foundational knowledge about the phenomenon of sweetness in coffee.

Read the full article on SCA News and 25.

Professors CARLOS CARPIO, PhD and LUIS SANDOVAL, PhD worked with BRENDA MAMANI, MSc to ask: what are the living wages in El Salvador and Honduras, and how would current total costs and profitability of coffee production be affected if farmworkers were paid living wages?

Read the full article in the Journal of the American Society for Horticultural Science.

In Honduras and El Salvador, coffee (Coffea arabica) is one of the leading agricultural exports, and the share of specialty coffee is growing each year. However, despite the importance of specialty coffee production and exports, there is a knowledge gap regarding its cost structure and profitability, particularly those associated with labor costs. The specific objectives of the study were to determine the cost structure of specialty coffee in Honduras and El Salvador and to estimate the costs and profitability of producing specialty coffee in these countries. A semi-structured survey instrument was administered to 14 farmers in Honduras and El Salvador selected as a convenience sample to represent different farm sizes, regions, and specialty-conventional and organic production systems. Specialty-conventional refers to high-quality coffee with or without certifications. Then,cost-profitability models were developed using an economic cost approach, which considered cash, noncash cost, and the opportunity costs of inputs. The results showed that although both countries are neighbors and economically and culturally similar, the cost structure of producing specialty coffee differed significantly. Costs were lower and profits were higher in Honduras than in El Salvador, and the specialty-conventional coffee production system was more profitable than the organic production system.

Read the full article on the SCA Portal.

Coffee Science Foundation Executive Director PETER GIULIANO sat down with DR. MACKENZIE BATALI, lead author of a recent milestone study, “Sensory Analysis of Full Immersion Coffee: Cold Brew Is More Floral, and Less Bitter, Sour, and Rubbery Than Hot Brew,” of the Coffee Science Foundation’s project, “Towards a Deeper Understanding of Cold Brew” to learn more about the process and the results of the study.

Cold-brewed coffee has become a mainstay of the specialty coffee experience over the past decade. Along with the popularity of cold brew, however, has come questions: How does cold-brewed coffee differ from hot-brewed coffee? Are the differences chemical, or sensory, or both? And how can our industry develop guidelines and best practices for excellent cold-brewed coffee?

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.

Read the full article on the SCA Portal.

Assistant Professor CHRISTOPHER H. HENDON shares the theory underpinning an ongoing Coffee Science Foundation research project, supported by Simonelli Group, toward deepening our understanding of espresso extraction.

Watch the full session from Re:co 2022 on SCA News

As home coffee consumption continues to increase even as pandemic restrictions ease, so too has our interest in understanding packaging (an element of the coffee experience making its way consistently into the home) through a multimodal lens. Dr. Fabiana Carvalho introduces an ongoing study, conducted in collaboration with the Coffee Science Foundation, exploring the effect of packaging on the perception of specialty coffee and explains why we need to expand our concept of "functional" packaging beyond simply keeping coffee fresh.

Read the full academic paper in Foods, an international, scientific, peer-reviewed, open access journal of food science.

Cold brew coffee is often described as sweeter or less acidic than hot brew coffee. Such comparisons, however, are potentially confounded by two key effects: different brew temperatures necessarily change the extraction dynamics and potentially alter the resulting brew strength, and different consumption temperatures are well known to affect perceived flavor and taste. Here, we performed a systematic study of how extraction temperature affects the sensory qualities of full immersion coffee. The investigation used a 3 × 3 × 3 factorial design, with coffee from three different origins representing different post-harvest methods (washed, honey-processed, and wet-hulled), each roasted to three different levels (light, medium, and dark), and each brewed at three different temperatures (4 °C, 22 °C, and 92 °C). All coffees were brewed to equilibrium, then diluted to precisely 2% total dissolved solids (TDS) and served at the same cold temperature (4 °C). We find that four attributes exhibited statistically significant variations with brew temperature for all origins and roast levels tested, with bitter taste, sour taste, and rubber flavor all higher in hot brewed coffees, and floral flavor higher in cold brewed coffee. However, there were strong interactions with origin and roast, with several additional attributes significantly impacted by temperature for specific origins and roast levels. These results provide insight on how brew temperature can be used to modulate the flavor profile of full immersion coffee.

Read the full article on the SCA Portal.

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).