It’s been around for centuries but it seems like beer has never been more popular. Microbreweries are cranking out special stouts, IPAs, lagers and pilsners. And the flavors and aromas of each of those brews all come down to chemistry. This week, in honor of St. Patrick’s Day, Reactions takes on craft beer chemistry. Big thanks to Matt Hartings, Ph.D., professor of chemistry and home brewer extraordinaire. For more beer chemistry, check out this fantastic graphic from Compound Interest.