July 25, 2014

Prof. Karl Siebert Knows Why Your Beer Is Flat

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By KATHLEEN BITTER

The way your beer foams as it leaves the bottle, can or keg this weekend is no accident, according to Prof. Karl Siebert, food science.

“Brewers work really hard to have good foam,” says Siebert.

According to Siebert, beer foam is measured using a variety of factors, from the volume of foam produced to how long the foam lingers to how well the foam sticks to the side of the glass. Generally speaking, brewers like see a long-lasting foam. For instance, Guinness is famous for its excellent foam, according to Siebert.

Prof. Karl Siebert, food science, says a variety of factors can influence the foam quality of a beer, including alcohol content and pH. (Benjamin Norman / The New York Times)