Piping hot science: Coffee or tea?

Abstract

A fine grind Americans drink more than 491 million cups of coffee per day, according to a 2023 report from the National Coffee Association, including the many cups of joe that scientists consume before beginning their daily research grind. One popular coffee-brewing technique is known as espresso, in which water at a near-boiling temperature is pushed through a bed of ground coffee beans at multiple atmospheres of pressure to produce a piping hot drink. Viewed through a scientific lens, the water acts as a solvent in this method to extract the molecules responsible for espresso’s popular bitter flavor. Conventional coffee-brewing wisdom holds that the finer the grind of the coffee beans, the richer the flavor—and science seems to find that line of thinking sensible, as a finer grind provides more surface area for water to dissolve coffee chemicals to make your espresso extra tasty. Not so fast, say leading coffee