Afraid to cask?
Thursday 08 March 2018
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What links a fire engine and cask beer? A Dutch inventor by the name of John Lofting, that’s what. In 1688 he patented a fire hose and engine for extinguishing fires, and by 1691 he did the same for an engine “for starting of beers and other liquors which will deliver from 20 to 30 barrels an hour which are completely fixed with brass joints and screws at reasonable rates” (so says The London Gazette). The invention brought cask beer into the industrial world and it works so well that the “beer engine” still in use today in pubs across the world. It is unsurprising, then, that casks have earned the reputation of being somewhat fuddy-duddy, especially in light of newer kegged beers. But done right, they can pull off a remarkable pint.
In Lofting’s day, casks were made of wood, but today they are almost all metal. They have two outlets, or plugs: the shive, for pegs or ‘spiles’, and the keystone, where a tap goes. Ian Morton, owner and brewer at Maregarde Brew Co., a small craft brewery in Homerton, London, working with about 50 casks a month, explains, “Casks will generally be wedged in their serving position and left for at least 24 hours to settle. A small, hard wooden peg called a spile can then be hammered into the shive to break its seal and then replaced with a soft spile to allow the cask to vent carbon dioxide. Later, the cask is tapped to allow for tasting the beer and then serving once it’s at the correct level of carbonation.”
The time allowed for settling is important for two major reasons: to start a secondary fermentation, called conditioning, and to allow any proteins, brewery sediment and yeast to sink into the belly of the cask. This is known as letting the beer ‘drop’ or ‘go’ bright and the time it takes depends on how strong the beer is, how vigorously it ferments and how much it’s been shaken about during transport. Some beers will be ready to serve once the beer drops bright, many others will need longer, up to 10 days, before they are properly conditioned and ready to tap.
Conditioning usually takes place below ground, in a cellar if the venue has one. The beer engine simply allows the liquid to reach the customer at ground level; as the bartender reaches for the pump handle and pulls it back, beer is drawn through a tube, or ‘line’, into the airtight piston chamber that’s at the heart of this great machine. At the same time air is pushed into the system. There’s a one-way valve that holds the beer tight within the piston until another pull of the handle, when the beer is released, gushing out of a further one-way valve, flowing through to the spout as more beer follows behind to fill the void in the piston chamber. Air flows the other way, out through the chamber and down the beer line to the cask, replacing the lost beer - for every pint of beer dispensed, a pint of air goes into the cask, adding to the pocket of already-present carbon dioxide. It takes three or four pulls for a perfect pint to be poured, and just a little strength from the bartender.
Pubs have a big responsibility to get cask beer right. Casks should be kept at temperatures far below room temperature - about 11°C to 13°C is right, which is why lovely, cool cellars are used. Too warm, and the yeast will work overtime to produce flavours that are overpowering. Plus, if too much carbon dioxide is made, the cask will “pop its shive” according to Ian, and maybe even spill its contents. What a waste. But, if the cellar is too cool, the yeast will not be able to work its magic and ferment the remaining sugars, giving off zero carbon dioxide. And no one, really, likes completely flat beer.
Ordering the right amount of cask beer is also crucial. While keg beer can last a long time since it is forced out with pressured carbon dioxide and nitrogen rather than air, cask beer lasts three to four days maximum. Once a beer is tapped and served, it’s a race against time before the beer goes stale. Oxidisation of beer creates vinegary flavours, and forms diacetyl that imparts a buttery or butterscotch flavour. Consequently the beer will be dull, unpleasant and unpalatable - unless you like the taste of butter in your beer, which some traditional cask ale drinkers have become used to.
“The pub plays an absolutely vital role in terms of what makes a good or bad cask beer,” says the Campaign for Real Ale (CAMRA). “Cask beer is a live product with a very short shelf life. It therefore requires skilled handling to control the stock levels so that beer is available when needed but not hanging around for too long and losing its flavour”. Casks come in several sizes: a ‘pin’ contains 4.5 gallons; a firkin contains 9 gallons; a kilderkin contains 18 gallons; and a barrel 34 gallons, so pubs have many choices to suit their turnover. “If your cask ale is warm and flat, it's likely out-of-date and not been stored correctly,” says CAMRA.
The duty of care that pubs have towards a cask system doesn’t stop at closing time either. “Keeping all the equipment in contact with the beer scrupulously clean is also paramount,” advises CAMRA. At the end of the night, the soft spiles are replaced by hard (to slow down nasty oxidisation) and cleaned. The lines between the cask, piston and pump need to be cleaned at least weekly to prevent build up of yeast and bacterial growth that may damage the beer. Line cleaner is a chemical solution that often comes with an indicator to show the presence of yeast. Shives should also be kept clean with food sanitiser, particularly on new casks, as well as the hard spiles and taps.
One final job that the cellar manager needs to do is to tilt any cask once it’s about two-thirds empty. The cask needs to be angled so that the back is higher than the front by around 7cm, which can be done manually with blocks, or using weighted racks that move up a touch when the cask weighs less than a certain amount. This lets the remaining beer get closer to the tap without disturbing the sediment at the bottom, so it can all be sold with the minimum of waste. Even so, the rule of thumb is to expect a 72-pint firkin to yield only 66 drinkable pints.
If this system sounds complicated and hard work, then, it is. There is a simpler system though: the gravity pour. It’s useful for venues that don’t have a ‘classic pub’ layout with a cellar, such as sports venues, smaller bars or festivals. Instead of putting in a tap and a line, pubs will knock in a spigot that can be turned like a tap to pour beer directly from the cask. Gravity pulls it straight down into the glass, simples. It requires very little setup or take-down and not even a bar top, just somewhere to rest the cask. And no line cleaner
What makes a cask beer great isn’t just down to the pub, though, it starts in the brewery. After cask beer finishes its primary fermentation, it’s called “green”. It’s chilled down to 8-12°C and then racked off into casks - though some breweries will do a part-condition in tanks beforehand. Racking leaves behind most of the yeast, with just a small amount left suspended in the beer.
Getting the yeast count right is key - a typical value is 0.5-1 million cells per ml. A small, measured amount of sugar is added for the secondary fermentation at the pub. Finings go in to help clarify the beer, binding together proteins and other residues. Sometimes dry hops are added at this stage for a flowery hop note in the finished beer (requiring a dry hop filter to be added to the tap when it comes to serving). The unpasteurized beer is then sealed (this is the seal that’s broken by the hard shive) and put in a big, refrigerated vehicle for the trip to the pub.
For all its virtues, there are big downsides to breweries making cask beer. For a start, it doesn’t make much money, because of the wastage that can occur, and the ‘traditional’ prices that are charged at the pub for a pint (often significantly less than for kegged beers). It also takes a lot of effort. A cask brewer has to trust every person down the chain: the transport, the person who unloads casks off the van, the cellar manager and even the person responsible for cleaning the lines.
Major breweries tend to stay away from the lower profits and more complicated operations required to make cask beer. Even smaller craft breweries have moved away from cask as they’ve grown. Three months ago, Northern Monk Brew Co. said it was making only a “very, very small amount of cask beer”. On New Year’s Day 2017, Manchester’s Cloudwater Brew Co. announced it would no longer be making cask beer. Stats published on the brewery’s blog offered its DIPA as an explanation: “We lose on average 22.19% of each batch to yeast growth and dry hopping. We have, miraculously, managed to lose as little as 12%, but we’ve also managed a shameful loss of 39% on one occasion.”
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