Now, know if your beer has gone stale with this new app

Beer will never taste as good as it does in a brewery's tap room, but one should be able to judge how fresh it is and try to avoid stale beer. Now, there is an app so that you don't miss the "drinking window" of a beer.

Chemists at the Complutense University of Madrid have developed a method that allows brewers to measure the freshness of beer, using a polymer sensor that changes colour upon detecting furfural, a compound that appears when this beverage ages and gives it a stale flavour. The sensor can be controlled from a smartphone app also created by the team.

The researcher points out that up until now brewers have measured furfural, a chemical compound that appears during the aging process of beer and gives it a stale taste, and other freshness indicators using methods based on chromatography techniques. "But these methods involve the use of expensive equipment and sample preparation is very time-consuming," researcher Elena Benito-Peña highlighted.

The system developed by the researchers at the UCM consists of sensor discs that detect the presence of furfural in beer. These sensors, made from a polymer similar to the one used to manufacture contact lenses, have been designed to change colour (from yellow to pink) when they come into contact with a beer containing furfural.

The team has also created a mobile app for Android smartphones that, by taking a picture of the sensor disc, allows for the identification of the amount of furfural present in the beer. With this data, the degree of freshness can be determined.

The application is available as open source, meaning that any programmer can utilise and modify it to be used on other platforms. In the future it will also be available for Apple IOS.

Benito-Peña recounts that the idea of developing the new method came about following a meeting with Mahou-San Miguel in which the company spoke about the technical difficulties they were having in detecting furfural directly at the production facilities.

The results of the tests on the new system "have been very satisfactory," says the co-author. "The measurements have been taken using samples sent directly from the brewing company with different production dates and distinct degrees of aging. These same samples were also sent to a laboratory where they were analysed using gas chromatography coupled with mass spectrometry. The results we obtained were completely comparable," she emphasises.

The method was initially developed for brewing companies. "Especially, because the global market for this product is huge. But it can also be used with other food products such as honey, milk, coffee, etc.," indicates the researcher.

The study is published in the journal Analytical Chemistry.