How To Make The Perfect Cup Of Coffee, According To Mathematicians' Calculations

Mathematicians work on a lot of important stuff, from developing complex financial models to understanding the structure of our universe, but one group of scholars is focusing on what really matters: coffee. Mathematicians are researching how to make the perfect cup of coffee, and it turns out that achieving caffeinated perfection is more complicated than you might think — and not only because every coffee lover’s idea of “perfect” is a little bit different.

In a study published in the SIAM Journal on Applied Mathematics, mathematicians Kevin Moroney of the University of Limerick, William Lee of the University of Portsmouth, and colleagues set out to discover how to make the best cup of joe. There are lots of different methods of brewing coffee, but, in general, coffee is produced through extraction — you grind the coffee beans and use hot water to pull the flavors of the coffee (and the caffeine) out of the grounds.

Focusing on drip filter machines, the researchers decided to see how math could shed light on the extraction process and how to optimize it for the best result. “Our overall idea is to have a complete mathematical model of coffee brewing that you could use to design coffee machines, rather like we use a theory of fluid and solid mechanics to design racing cars,” Lee told BBC News.


Lee pointed out that we already have some basic understanding of how issues like grain size affect the taste of coffee — grounds that are too small can create bitterness, while grounds that are too large can lead to coffee that’s watery and weak. His aim is to make that subjective knowledge more quantitative. “[R]ather than just saying: ‘I need to make [the grains] a bit bigger,’ I can say: ‘I want this much coffee coming out of the beans, this is exactly the size [of grain] I should aim for,” he explained.

The extraction process is more complicated than one might expect for a beverage consumed by 83 percent of American adults. “The really surprising thing to us is that there are really two processes by which coffee is extracted from grains,” Lee told BBC News. “There's a very quick process by which coffee's extracted from the surface of the grains. And then there's a slower tail-off where coffee comes out of the interior of the grains.”


The study doesn’t offer a magical formula for making perfect coffee at home, but the authors hope that their research will eventually lead to making drip coffee machines that produce better results. These machines would be able to adjust the flow of water to optimize extraction for a given size of coffee grains, or, in a machine with a grinder, play around with both grain size and the water flow to create the ultimate cup to suit the drinker's tastes.

The research here is ongoing — Lee and his colleagues are now looking into how the shape of the coffee bed in drip filter machines affects the extraction process, and therefore the flavor of the coffee. It may be a while before we have machines that can perfectly brew cups of coffee to our individual tastes, but until then, I have a feeling that most coffee lovers will continue to take their caffeinated lifeblood in any way they can get it — drip machines, pods, French presses, IVs, whatever works.


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