A study that dropped today suggests that coffee purveyors seeking to maximize good taste and consistency have generally been using way too much coffee.
The research — led by a 10-member international team performing mathematical modeling and pulling hundreds of espresso shots — suggests that the key to making consistently good espresso is using far less coffee at a coarser grind, with less water and a faster brew time than found in established methods.
The recommendations of the study — which boil down to about 15 grams of coffee with shot times from seven to 15 seconds — run contrary to nearly all published standards related to espresso preparation and extraction, including the classic Italian espresso methods and more newfangled approaches from groups like the Specialty Coffee Association.
While coffee professionals might be quick to dismiss the research as impractical academic wanderings, it should be noted that the lead author is University of Oregon chemist Christopher Hendon, whose previous scientific work on water composition and grind particle consistency, among other subjects, has been hugely influential in the industry.
“The real impact of this paper is that the most reproducible thing you can do is use less coffee,” Hendon said in an announcement of the study, which was published online today in advance of an upcoming print version in the scientific journal Matter. “If you use 15 grams instead of 20 grams of coffee and grind your beans coarser, you end up with a shot that runs really fast but tastes great. Instead of taking 25 seconds, it could run in 7 to 14 seconds. But you end up extracting more positive flavors from the beans, so the strength of the cup is not dramatically reduced. Bitter, off-tasting flavors never have a chance to make their way into the cup.”
Before the hundreds of test shots were pulled at the Tailored Coffee Roasters headquarters in Eugene, Oregon, researchers drew upon electrochemistry theory, likening the movement of caffeine and other molecules through a packed bed of espresso to lithium ions moving through the electrodes of a battery.
“Our model lets us take the leap from a very small particle size, less than the size of a hair, and solve a series of equations that tell us how much mass can be transported out of these little particles,” study co-author Jamie M. Foster of the University of Portsmouth (UK) wrote.
For the day-to-day dialing in of espresso within coffee shops, the research is being presented as potentially transformative. Hendon wrote that baristas often begin with a grind setting then modify water volume and flow parameters. “That usually involves a reduction in shot volume to get a desired flavor,” the study announcement stated. “However, if the volume is too small, [Hendon] said, an operator should grind coarser and repeat the volume-reduction process to reach a bigger drink of lower concentration but reproducibly tasty.”
Based on the research team’s conclusions, brewing espresso to ideal parameters for repeatability and taste would result in 25% less coffee used. The researchers estimate that 124 million espresso shots are pulled in the United States each day, and that such savings would result in $3.1 million per day for the retail coffee industry.
Of course, a 25% reduction in espresso consumption in the U.S. alone would dramatically transform global markets, all the way down to individual coffee farmers.
“For the local shop owner, this is an opportunity to save a lot of money without sacrificing quality,” Hendon wrote. “For the roaster, this is an opportunity to reflect on the approach to roasting and how people are brewing their coffee. For the producer, this should encourage them continue to produce high-quality coffee that can earn them the most money, knowing that more people will have access to it.”