These models suggest that brewing good coffee can be boiled down to a simple rule: grind beans more finely if the coffee is too watery or use a coarser grind if it tastes too bitter. But that’s not what was the most important to come out of this study. Because the researchers performed a quantitative analysis, not just qualitative, their model can determine the exact grain size to brew a coffee of some desired properties. If manufacturers take a hint, then in the near future you might be able to buy coffee machines which grind your coffee per your desired taste, oscillating between bitter and watery. Barista-grade coffee coming out of every kitchen — that could really happen!
Another interesting conclusion is that there are two physical processes that influence the brewing.
“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,” said Dr Lee.
Next for the researchers is studying how different dripping methods influence brewing. For instance, what’s better: pour hot water dead center or sprinkle it like a shower? Should the machine have a flatbed or should it be conical?
The findings appeared in the SIAM Journal on Applied Mathematics.