Testing Beer DNA

In the past we’ve talked about diacetyl, a chemical that can appear in beer and may mean that the beer has gone bad. But there are a plethora of other chemicals and bacteria like pediococcus that can ruin a beer; a brewer may not know until it’s too late, because you can’t see them with the naked eye. However, some brewers like Russian River and Victory are trying to stay ahead of these little buggers by testing their beer’s DNA.

Before DNA testing, brewers used a system called plating, where they’d take a beer sample, put it onto a plate of bacteria food, and wait for about week to see what happened. If a bacteria colony blossomed in front of their eyes, then they knew they had a bad batch.

To speed up the process, several companies have developed testing kits that reduce the time to several hours. These kits range from the BrewPal at the low end for around $5000, to bigger systems from Sigma Aldrich and Hybriscan which cost anywhere from $30- to $40 thousand. Some systems only look at live bacteria, while others look at both live and dead.

All of these systems offer various capabilities, but they’re all based on a technique called polymerase chain reaction, or PCR for short. PCR was developed in 1983, and led to other breakthroughs in gene sequencing, gene cloning, and other DNA-based diagnostics, as well as testing for bad olive oil and caviar.

Simply put, PCR is a process that photocopies bacterial DNA through cycles of heating and cooling, which prompts one strand of DNA to replicate itself continuously for about two to three hours until it becomes more detectable by a reader looking for these bacteria.

So, within about three hours, a brewer can know if they have a bad batch of beer, rather than the week it used to take. And because time is money, a brewer can avoid pouring thousands of dollars of time, ingredients, and floor space down the drain.

Sources: Popular Science, The Verge, Bitesize Bio