This App Can Tell When Beer Has Gone Stale

Despite the fact that beer is fermented, it can and does go bad over time, unlike other alcohols including wine and liquor. There are all kinds of ways beer can deteriorate and become undesirable; light, for example, can interact with hops and create the infamous “skunked” flavor. That can be fought with darker bottles, but oxidation – the interaction of beer with oxygen – remains a struggle. Oxidized beer has a particular, not-so-nice flavor referred to within the industry as a “papery” or “cardboard-like” taste.

Oxidation is just a fact of life, very literally; it’s something that will happen. But no brewer, either of the home or commercial variety, wants to sell, distribute, or drink oxidized beer. Until now, a fairly surefire way to test batches of beer for oxidation was to look for the presence of furfural, a chemical compound that’s always present in beer but which skyrockets as beer freshness goes downhill. Furfural isn’t responsible for that papery flavor, but since it’s heavily correlated, it can serve as a good warning sign.

Previous work, like this one from 2009, has indicated that you can detect furfural with high-performance liquid chromatography, a chemical technique that pumps liquid through various substances to measure absorption. As you might expect from that deliciously sci-fi name, high-performance liquid chromatography is not really accessible to the layman; it doesn’t require exactly the most expensive equipment, but it does require some, along with specialized skill – both of which could be outside the range of acceptability for small craft brewers and certainly for homebrewers.

Researchers at the Complutense University of Madrid have come up with another way. They’ve created little discs, which they say are similar to contact lenses, that change color when in the presence of furfural. The discs are also amount-sensitive, important given that even the freshest beer does have some furfural in it; the precise shade of color the disc turns can be used to detect to a fairly accurate degree the amount of furfural in a sample of beer.

Even better: The researchers have created a smartphone app (Android only, for now, though they say an iOS version is on its way) that uses the phone’s camera to snap a pic of the disc, and then analyze the color to figure out how much furfural is in the sample. The researchers say this method was initially designed for brewing companies, but if the final product is low-cost enough, it’s not hard to see how this could be of great interest to homebrewers as well. And, of course, all beer lovers. It’s not available yet – searching for the app in the Google Play Store is fruitless at the moment – but with any luck it’ll be out there, fighting the good fight for fresh beer, soon.