Stale beer no more: This app can tell you when your brew's past its prime

There’s a good chance your tastebuds would tell you when you’re drinking stale beer, but now science has come to the rescue to spare them that pain.

You can thank the chemists at Spain’s Complutense University of Madrid, who have developed a sensor and Android app that can tell you when you shouldn’t even bother having a sip.

To monitor a beer’s freshness, brewers often use chromatography techniques to measure indicative chemicals including furfural, a compound that appears during the aging process and gives beer a stale taste. The problem is, those techniques can be time-consuming and expensive.

In this new work, published recently in the journal Analytical Chemistry, the researchers devised a system including sensor discs that detect the presence of furfural in beer. Made from a polymer similar to what’s used to manufacture contact lenses, the sensors change color from yellow to pink when they come into contact with a beer containing furfural.

The team has also created an Android app to help assess where a beer falls on the freshness spectrum. Take a picture of the sensor disc, and the app tells you just how much furfural is present—and how fresh the beer is. The app is available as open source, meaning that any programmer can use and modify it for other platforms. An iOS version will be available in the future, the researchers say.

The technology was initially developed for brewing companies through a partnership with the Mahou-San Miguel brewing company, but it could also be used with other food products, including honey, milk and coffee, the researchers said.