In the latest in our series Nigel Huddleston looks at the role of the cask in production

Speak to fans of British beer and they’ll tell you that cask conditioning produces beers with finer aromas, fuller flavours and deeper character than those that aren’t, but what nobody ever bothers to explain very often is why.

Conditioning is the process a beer goes through after fermentation to make it ready for dispense. For draught beer, it can be either conditioned in the brewery or in the cask. The former is done in conditioning tanks, in which the beer is cooled and the yeast sediment filtered out, before being pasteurised and put into a sealed keg to be dispatched to the pub.

The common criticism among overly-serious beerlovers is that these processes combine to remove some of the better flavours and aromas from a beer. The alternative, cask conditioning, is almost entirely associated with British ale, and involves inducing a secondary fermentation in the cask. The beer is ‘live’ with active yeast when it arrives at the pub, and undergoes its conditioning in the pub cellar.

Before that, back at the brewery, the beer is racked off – unfiltered and without being pasteurised – into barrels in which a secondary fermentation process takes place. While the beer sits in the pub cellar, the yeast is still working on the fermentable sugars in the brew to produce alcohol and carbon dioxide.

It also produces some of the fruitier flavours and aromas often associated with cask-conditioned beer. Sugar is sometimes added at the time the cask is filled to assist the secondary fermentation, and extra hops are sometimes introduced too, to produce greater hoppy aroma in the beer.

When the cask is filled, a form of gelatine known as isinglass is added. This is made from the internal organs of fish, particularly the sturgeon. Its role is to attract the yeast sediment to the fat bit (or belly) of the cask, giving the beer clarity when it’s served. That’s why cask beer needs to be stored lying down. The use of isinglass is why some regard real ale as nonvegetarian friendly.

Sounds great so far, though I’m not 100 per cent about the fish organs. What’s the catch? The main drawback is that because the beer is ‘live’ after it leaves the brewery, it needs to be treated with care, stored at around 10-12ºC and consumed relatively quickly. Leaving the beer too long before serving can cause it to lose some of its better flavours, and poor storage can affect the level of carbonation, causing too lively or too flat beer.

It’s because cask beer has a limited shelf life and doesn’t like being knocked around too much, that drinkers refer to beers “not travelling well,” meaning that they taste better in pubs closer to the brewer than those far away. In short, from the pub’s point of view it’s more fiddly than sticking a keg of lager or smoothflow ale on. From the drinker’s side of things, if the pub isn’t skilled in keeping and serving cask ale and doesn’t have a high enough throughput to ensure the beer is served fresh, then the result can look and taste closer to a pint of vinegar than a pint of great beer as the brewer intended.

What happens once cask beer’s in the cellar?

For example, the cellar person has to use his skill and judgment to control the condition of the beer in the cellar. He does this by driving a small wooden peg called a spile into a hole in the cask.

If he uses a soft wood peg he can allow some air into the cask, reducing the CO2 fizz to more desirable levels. By using a hard wood spile he can contain CO2 within the cask and give it a bit more sparkle. If you’ve ever had bottle conditioned beers (that continue fermentation in the sealed bottle) you might have occasionally found them over-fizzy, because the yeast is working to produce CO2 which has no means of escape.

Back in the cellar, when the cellar staff are satisfied that the beer is at the right condition, a tap is knocked into a second hole and it will be connected to the dispense system. Most standard strength beer needs to be consumed within a few days from this point.

So is cask-conditioned beer the same as real ale?

Almost, but not quite. All real ale is cask conditioned, but not all cask-conditioned beer is ale. It’s possible to cask condition lager as well, and there is a tiny but growing band of brands available on the British market, the most high profile of which in recent times has been Cain’s Finest from Liverpool.

Cask conditioned beers do tend to be ales, however, and while many are traditional best bitters, the term covers a multitude of styles including India pale ales, milds, porters, stouts and increasingly-popular “golden ales”.

Although it sounds like something you’d have got in Ye Olde 17th Century Ale Shoppe, the term real ale is relatively modern, having been coined hand-in-hand with the formation of the British pressure group the Campaign for Real Ale in the early 1970s, an era when cask conditioned beer were in decline as the United Kingdom’s brewers put their production and marketing efforts behind keg (ie, brewery conditioned) beers. But until it came up with the pretty neat term “real ale”, the CAMRA acronym actually stood for the Campaign for the Revitalisation of Ale.

My local’s got no handpumps. Does this mean it doesn’t sell cask-conditioned beer?

Not necessarily. The vast majority of cask conditioned beers will be served through traditional hand-pumps, though this is not necessarily always the case. The handpump operates a device which draws half a pint of beer. Two pulls should pull a whole pint. Sometimes the beer is forced through a swan-necked line behind the bar and through a nozzle known as a sparkler. This agitates the beer and produces tiny air bubbles that form a creamy head.

Certain brews, particular from northern England, are designed to be served in this way, and a sparkler shouldn’t be used for beers that aren’t brewed specifically for their use. Because the process of pulling a pint draws air into the system, it can lead to oxidisation of the beer if throughput is slow. For this reason some pubs use a device called a cask breather which forms a layer of carbon dioxide on top of the beer to protect it, though purists argue this harms the flavour of the beer.

Also in northern parts of England, there is still some use of measured electric pumps, which give the impression of keg or nitrogenated beer, but actually are just a way of portioning out cask beer. If in doubt, your friendly bar person should be able to set your mind at ease.

Article is from Issue 6 of Beers of the World Magazine