As my fellow coffee lovers may know, espresso is made by forcing water through a bed of coffee particles, which extracts chemicals like caffeine and sugars. Smaller particles and higher pressures usually mean higher extraction and stronger cups, but experienced baristas know that grinding coffee finer doesn’t always produce a stronger cup. Baristas, but only now have scientists, in collaboration with the coffee community, succeeded in quantifying this effect.
With a mathematical model backed by experiments, researchers finally confirmed the theory that baristas have held for years; that high pressure (often achieved by adding more or finer grounds) and irregular particle size can cause flow channels to form, resulting in uneven wetting of the coffee, and ultimately making a weaker, less tasty brew.
Researchers hope this model helps make coffee more delicious with less waste — and the success of this work demonstrates the importance for clear science communication as fruitful collaborations can often be found outside academia.