Physicists unlock another clue to brewing the perfect espresso

Many variables can affect the quality of a steaming cup of espresso, including so-called "channeling" during the brewing process, in which the water doesn't seep uniformly through the grounds but branches off in various preferential paths instead. This significantly reduces the extraction yield and thus the quality of the final brew. Scientists from the University of Warsaw have gleaned insights into the underlying physics of channeling that will help coffee lovers achieve more consistent results when brewing espresso. They presented their preliminary findings at the American Physical Society's Global Physics Summit in Anaheim, California, this morning. As previously reported, there's an official industry standard for brewing espresso, courtesy of the Specialty Coffee Association, which sets out strict guidelines for its final volume (25–35 mL, or roughly 1 ounce) and preparation. The water must be heated to 92° to 95°C (197° to 203°F) and forced (at a specific pressure) through a bed ... Read full article.