Wednesday 17 March 2010

Immobilised Yeast

A Burton-based brewing company have recently announced a new innovation in brewing. They are applying immobilised yeast technology to ‘condition’ beer in the cask. Their new system will mean that beer is always bright as the yeast is trapped inside a calcium alginate gel.

Beer can flow across the gel matrix to the yeast and the yeast fermentation products back into the bulk beer. If the beer is bright before the immobilised yeast goes in then I assume that it has been processed in the brewery to remove the yeast of primary fermentation (fining, centrifugation and/or filtration). The question is then, is this cask ale or simply filtered beer with a system to prevent oxygen damage? Having beer which is readily bright will make running a cellar slightly easier. This new system will of course still need the beer to be sold in less than 5 days and require good cellar temperature and hygiene control. I think therefore that it won’t convert very many non-cask pubs to ‘cask’ ale.


Whorst said...

Stu, I have questions for you. Is cask conditioned beer not at its best when it's dropped bright? When it's dropped bright, do you think it can still lead to green, underconditioned, immature and downright flabby beer?

Stuart Howe said...

Yeast affords cask ale protection from the deleterious effects of oxygen(stale flavour). In a cask the yeast sediment provides this protection. If you decant the beer off of the sediment (rackbright), the protection is lost and beer stales rapidly. The process of decanting the beer off of the yeast also knocks out some of the CO2 and incorporates oxygen into the beer. Rackbright beer therefore has less fizz, tastes less fresh and deteriorates much more rapidly than cask conditioned ale. The Ca+alginate yeast beads should act in the same way as cask sediment.

Nice Hampton by the way. Nearly as big as mine.

Whorst said...

Nice, we have something in common!

I was referring to myth and legend that some people come up with regarding cask conditioned beer. In your opinion, when does a beer become mature?? I know it largely depends on gravity, but is it not subjective? What the hell is green beer? Can a bright, naturally conditioned beer be green? I suppose it depends on your definition of green, which is again, subjective.

I am trying to dispel myths that people come up with that correlate with nothing scientific. Cask ale failure is largely due to lazy publicans and the beer not moving, which leads to lack of condition, which leads to warm vinegar.

Cheers, Kevin, sometimes known as Whorst

Stuart Howe said...

I understand green to mean 'unripe'. Any brewer who cares about how the consumer perceives his beer will make sure that the beer is 'ripe' before he lets it out to the trade. At Sharp's we condition in the brewery as well as the cask so we never send green beer out.

Maturation and staling are the same phenomenon viewed from a different perspective. I always say of our cask beers that fresh is best becuase we condition in the brewery. This may not be the case for breweries that rack green beer stright from FV and give it to the customer to finish for them.

I agree that some people in the trade talk a lot of sh1te about maturation in open casks and even argue that oxygen is involved in cask conditioning. Some are even ignorant enough to suggest that hop notes benefit from oxidation and extended storage. Just like the bloke at the bar who could do a better job of managing the England team, everyone is entitled to an opinion irrespective of their ability to reasonably or scientifically justify it. There are thousands of self-appointed beer experts with no real techical understanding of beer and brewing. Any brewer will tell you that casks, once vented should be empty as quickly as possible. The maximum time they should be kept on dispense is 5 days after broaching but that is pushing it.

It's all a matter of opinion really and you are at the mercy of the man in cellar. Some people like old flat oxidised beer. Some people like to to be tied up, beaten and used as a toilet but that doesn't make it sensible.

Anonymous said...

"Any brewer will tell you that casks, once vented should be empty as quickly as possible."

Indeed. What Whorst is trying to get you to say, however, is that all cask beer should be drunk right after it drops bright. As you say, you mature - condition - in the brewery. Not all brewers have the room to do that. Those brewers that deliver unmatured beer to the pub, their beer will need to mature in the pub cellar, and even after it has dropped bright it won't necessarily be mature enough to drink.

Stuart Howe said...

I see now what Kevin was talking about. This definitely could occur in some pubs particularly ones with high turnover, local to the brewery and particularly in the depths of winter when the supply chain is too cold for yeast activity. As a brewer I want as much control over my beer as possible so I won't let it out before it's mature so you shouldn't find that this is an issue with my casks.

I would like to add that I did get a bit carried away on my reply to Kevin and may have appeared to slate landlords. 99% of the landlords I have encountered have been consumate professionals and do know their art and I have the utmost respect for the job that they do.

One final comment about fast cask is that this beer will have been conditioned and stabilised before filtration or centrifugation in the brewery so you shouldn't have to wait for this to mature. I think it's a nice idea but resent the inferrence that unprocessed cask ale is an inherently troublesome product. I also resent Marstons implying that other brewers process their cask beer and don't admit it. I don't know of any cask ale breweries who remove all the yeast of primary fermentation. Some of the larger regionals centrifuge out a proportion but none render it bright.

Sat In A Pub said...

Thanks. Very informative piece. I'm certainly looking at Fast Cask with a different perspective now.

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