Happy New Year, cask whisperers! In a break from nurturing our house yeast and chalking up the brewing calendar, we grabbed a beer and some twiglets with our Head Brewer, Dan, and let him wax lyrical on cask beer and fermentation:

At the heart of British brewing is the history of the family or regional brewers and that history is inextricably linked to cask beer - a British brewing tradition. This method of dispense and supply is not inherent to British brewing traditions alone, but British cask beer with its live yeast and carbonation from secondary fermentation inside the cask itself, is a rare practice in the world today.

The landscape of beer was completely transformed through the industrial revolution and during the 19th century, advances in scientific understanding helped us attribute the nature of fermentation to yeast. Improved technologies then set the foundations for commercial brewing as we know it today.

Brettanoymces describes a particular non-sacchromyces yeast. It literally means ‘British yeast,’ and it was named owing to the fact that British brewers often had ‘wild’ yeast in their cultures. The pure strain cultures did not take off in Britain like they did on the continent when they were first developed by Hansen of Carlsberg in the 19th Century. As I write this, our house yeast culture still has a dual strain and when I think about cask beer, it is this heritage and history that makes it so special for me.

Cask beer nearly disappeared with the rise in popularity of keg beer. It can’t be ignored that filtered and pasteurised beer is much easier for brewers and supply chains to handle. Its shelf life is much longer for one! Unlike the previous rise of keg bitters like Watney’s Red Barrel, cask beer now has the increased challenges of much more choice and great-tasting keg beer to compete with in the modern market. Fortunately, there have been huge amounts of investment in the brewery over the years, which means the quality of our cask is second-to-none.

Cask beer itself requires much more attention. Over the years, brewers have come up with all sorts of ways to make things easier for publicans, such as fast cask or immobilised yeast gels that were heavy enough to sediment rapidly. They didn’t catch on. There is now the common technique of brewery-conditioned beer, whereby the secondary fermentation and carbonation is completed before the beer goes into cask. Some brewers may incorporate sugar priming and try to control the conditioning by fermenting all the sugar out before reintroducing a controlled amount to get the correct amount of carbonation, but there really isn’t any substitute for properly conditioned cask beer.

The Adnams way, is to control mash temperatures in the brewhouse and brewery fermentation conditions to leave the ‘right’ amount of sugar at the end of fermentation for the yeast to act on. Adnams isn’t the only brewer over the years to employ this technique, but what I would say, is this secondary fermentation in cask is pivotal in making a good beer into an exceptional one.

Some suggest that cask beer is flat, but the honest answer is that it really shouldn’t be. Yes, it’s going to be less effervescent than a highly carbonated Czech lager, but it should never be flat. I always suggest that those who serve Adnams cask beer employ vent pegs to assist with the level of venting. I’d also suggest running cellars at a temperature lower than the usual 11 to 13 degrees. In fact, this year we are going to push the boundaries on carbonation in cask by brewing some cask lagers for our 2024 collaborations.

I’d also suggest that everyone installs cask aspirators. If you don’t have them and you might want to make sure you use them with the cask lager, if not with all of our beers. We would fully help and support with this. By replacing air with CO2, the beer is protected in the cellar. The CO2 acts merely as a barrier to oxygen and losing that vital carbonation we all have worked so hard to encourage.

The ultimate challenge for cask beer is turnover. This category needs sustainable throughput like no other format does. The hope is that these lager styles will introduce cask to a wider audience to the marvels of cask. Because cask is unfiltered and unpasteurised, it retains so much more flavour. I think the lower levels of carbonation makes it much more approachable and subtle nuances in hops can be showcased in this format.

While we look forward to the coming year and innovating, one of the things I love about being a Head Brewer is being a steward - a custodian for all the heritage beers we inherit. To be honest, even a new beer moves quickly into the ownership of its customers. It is this feeling of ownership that is so lovely about beer in general.

I did see this transcend into the snacks trade during COVID, regarding the production of Twiglets. They definitely reduced the amount of marmite in the recipe owning to the fact there was a sudden lack of yeast supply, and I was one of those customers that was outraged. But this feeling of ownership is what makes it all so very special, and nothing embodies this sentiment more than our relationship with the Southwold Bitter drinker. We look forward to continuing to dry hop these casks with Fuggles. It might mean that as a result they require more care, but as a wise person once said, “This is the way.” And this is the way - the Adnams way, and we will continue to brew cask and not make any compromises.