New Research Unveils Surprising Relationship Between Finer Grinds and Weaker Espresso
In a recent publication, researchers have shed light on a counterintuitive discovery in espresso crafting: finer grinds may result in underdeveloped and weaker espresso. The culprit behind this phenomenon appears to be uneven extraction, as revealed by a study published in the American Institute of Physics' food-focused section.
This research builds upon a groundbreaking 2020 study that challenged conventional wisdom and standards regarding espresso recipes and extraction principles. Both studies employ mathematical modelling to examine how variables such as grind size, particle distribution, water pressure, and flow impact espresso extraction. Their aim is to enhance the understanding and control of espresso quality among coffee professionals while potentially reducing coffee waste in daily operations.
Led by researchers from the University of Huddersfield in the UK, the latest study provides fresh insights into how finely ground coffee can lead to uneven extraction. Conventionally, it was believed that finer coffee grounds, with increased surface contact, would result in greater extraction when pressurized water is forced through the coffee basket.
Expanding upon the findings of the 2020 study led by coffee-focused chemist Christopher Hendon of the University of Oregon, the new research introduced a model with two regions within a single coffee bed to explore the effects of unevenness.
"Our model shows that flow and extraction widened the initial disparity in flow between the two regions due to a positive feedback loop, in which more flow leads to more extraction, which in turn reduces resistance and leads to more flow," explained study co-author William Lee. "This effect appears always to be active, and it isn't until one of the regions has all of its soluble coffee extracted that we see the experimentally observed decrease in extraction with decreasing grind size."
The researchers from Huddersfield are hopeful that their work will pave the way for practical applications in the coffee industry. They plan to refine their model further to gain more detailed insights into this intriguing phenomenon. Once achieved, they aim to explore possible changes to espresso brewing methods that could reduce uneven extraction.
This research presents a fascinating shift in understanding the relationship between grind size and espresso quality. It opens up possibilities for refining espresso brewing techniques and optimising the extraction process, ultimately benefiting coffee professionals and enthusiasts alike.