Is PCR Better than Culture

You would expect me to say yes, obviously, but its horses for courses. Traditional culture methods although relatively slow, are easy to perform and cheap. The downside is they can pick up bacteria that don’t spoil beer and can miss ones that do.

The agar used although selective for spoilage doesn’t mirror whats in your beer (it doesn’t contain alcohol for instance). However if used right culture its a great tool for the brewer, especially so if its done on-site and used as part of an on-going risk based quality management system.

So where does PCR fit in, well its much quicker (hours compared to days), it doesn’t miss VNC bacteria and it only picks up the bacteria of interest. It can be used as an alternative to culture, or in addition to culture, and certainly that’s the trend we are seeing right now.

Many of the larger US craft brewers as well as the much bigger multinational breweries now have a variety of testing set-ups, some use culture, but are looking at the easier to use colour changing liquid media.

The advantage here is that the brewer can test every relevant part of the brewing process very easily and cheaply, only using PCR for bacteria identification or as a sense check. However we are also seeing some brewers e.g. Avery, Victory, Stone, and Russian River to name but a few, opting to replace culture altogether and now have basic PCR systems on-site.  We expect that over the next few years UK brewers to follow suit.

Future Trends

Craft brewers are by nature experimental, which comes with risks, so having better control over quality is essential. Better beer is good business, and more testing can only lead to better beer.

On-site testing ticks most of the boxes a brewer could want ticked. Its far more economical than using a contract lab, its as quick if not quicker in most cases, it can provide more or less the same information and if the brewer either has the skill base to use culture plates or opts for colour changing liquid media there is little in the way of initial outlay.

As a point of reference this is exactly what has happened in the clinical market place, where ‘point of care’ (on-site testing’) has become mainstream.

We have no doubt however that PCR will come to dominate the beer testing market, up until now the cost and expertise required have limited its use, but as PCR is now priced the same as laboratory culture methods, there is little stopping any craft brewer accessing this state of the art technology.

For the more adventurous brewers having access to their own systems could well be the next move. By the time this article is published, we will have released a real time PCR analyser, costing £3K capable of performing beer spoilage bacteria detection is hours.