A few days ago, I was sent an e-mail by a Head Brewer from a regional brewery commenting on the spate of exploding cans and product recalls that has hit the craft brewing industry recently.

One of his main concerns was that these product recalls would tarnish not just the breweries involved, but the entire UK craft brewing industry.  Until I received this e-mail, I hadn’t really considered it from this angle. However, after ‘chewing the cud’, I believe he has a valid point, particularly if somebody was injured as a result of an exploding vessel.

One thing I have always advocated and pushed for is fresh beer. Not only fresh beer, but beer which has had minimal processing and certainly has not pasteurised. As a brewer once said to me, ‘Pasteurisation allows brewers to sleep at night’.  What makes pasteurisation so attractive from a QA and safety point of view is that it doesn’t matter what has gone on upstream.

Even a beer infected at the last possible moment during packaging would have no issues, as it is heated sufficiently in its final container to kill any yeast or bacteria which may have been inadvertently introduced.  I know for a fact that some breweries in the past have not really worried too much about infections upstream, as they are relying on the pasteurisers dealing with bacteria once the beer is packaged.

Bottle conditioning used to be fairly common practice, but because of the inherent problems of bottle conditioning, it became a rarity.  This blog here: http://zythophile.co.uk/2010/01/15/a-short-history-of-bottled-beer/ quotes that in the 1970’s, there were only five brands of bottle conditioned beers available in the UK.  I suspect yet again that the reason to shy away from bottle conditioning was to ‘allow the brewers to sleep at night’.  Bottle conditioning certainly brings something to the table, namely improved resilience to oxidation and a softer, more natural form of carbonation.

Here is a relatively detailed explanation of bottled conditioning and the various ways to approach it: https://beerandbrewing.com/dictionary/iKSxvCoDdk/bottle-conditioning/   At Thornbridge, we centrifuge the beer bright, measure the CO2 level, then calculate the correct amount of sugar solution we need to add to obtain the desired level of in-pack carbonation.

Finally, we inoculate the beer with 0.75-1.0 million cells/ml of Champagne yeast. We approach wheat beers slightly differently, by ‘krausening’ each batch of wheat beer from a lager fermentation, but again making the necessary calculation to hit the desired level of CO2.

I mentioned earlier about the ‘inherent’ problems of bottle conditioning. Namely these are:

  • Introducing an infection into a previously microbiological clean beer. This could be either during the dosing of the yeast or sugar or a very small number of bacteria which, under bright conditions, wouldn’t cause problems, but as soon as there is any form of autolysis from the yeast it acts as a food source, reinvigorating the latent bacteria.
  • The refermentation of the sugars stalling, resulting in an under carbonated beer ( this is one of the reasons I would suggest always using fresh healthy yeast, rather than tired, stressed yeast from the primary fermentation).
  • The brewer incorrectly calculating the level of fermentable sugars, resulting in over carbonation, and in the worst case scenario – exploding bottles or cans.

Out of the three scenarios, it’s the latter which would give most brewers cause for concern. At first glance, it might seem that the obvious mistake would be to get the sugar calculation wrong, which of course could happen if a brewer was to get his decimal point in the wrong place or the sugar wasn’t weighed out or mixed correctly into the beer.

A more latent problem can be when the primary fermentation hasn’t reached its limit of attenuation, even though the brewer thinks the fermentation is complete.  So, if for example a fermentation stalled at 3 Plato and the brewer thought that his fermentation was complete, but for one reason or another the true level of attenuation was 2.0 Plato, this could equate to a significant increase in carbonation once the beer had fermented out.

The problem would only rear its head when the fresh, healthy yeast is added to the beer.  At Thornbridge, part of our QA system involves a limit of attenuation test of every batch of beer we produce.  Fermentations are a fairly hostile environment for yeast cells, with high levels of CO2, alcohol and pressure, and therefore there is always the chance a fermentation won’t reach its true level of attenuation.

In the limit of attenuation test, we provide optimal conditions, a high yeast count, constant agitation at a steady 20c for between 24 hours and 48 hours. The result from this test in theory would be the level the fermentation in question should attenuate to, all being well.

If we find a fermentation has a level of attenuation which doesn’t match the limit of attenuation test, then we have numerous weapons in our arsenal to complete the fermentation. These include rousing, krausening, or using a different yeast strain to complete the fermentation.  However, a beer would never be signed off for packaging without it reaching its limit of attenuation, or as near as damn it.

Although it appears that the number of product recalls within the industry have calmed down, I still don’t believe that the problems have been fully solved.  There have been a huge number of new breweries start up within the last two years and many of them are trying to run before they can walk, with no QA system and guided only by generic homebrew books and a desire to impress social media forums with wacky beer ideas and cool branding.

In addition, I have just heard a story from another country where a brewer added pure fruit puree to a beer and assumed because the beer had been filtered, there was nothing to worry about!  Can you imagine if Coca-Cola had this attitude?  An even worse scenario would be an exploding keykeg due to refermentation after packaging and this could have disastrous consequences.

As craft brewers become more and more ambitious with their beers, such as using Brettanomyces (a very latent yeast which can chew through almost anything) and adding fruit purees to beers, I believe it is key that they invest as much as possible in their QA system and learn as much as they can about their trade, before risking an idea on the general public.

No-one wants to see more recalls, but let’s get something straight: a product recall is not ‘great QA’ as some devoted beer fans commented on social media, but a necessary procedure for a brewery to carry out when the brewery QA system has failed completely.

What we do want to see are educated, skilled brewers creating innovative and exciting beers, brewed using the correct procedures – beers that excite the beer geeks whilst also making beer more accessible and attractive to all drinkers.  A rising tide lifts all boats!

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