A version of this article first appeared in Brew Your Own magazine December 98.

Cask Conditioning Tips

The ins and outs of cask conditioned ale brewing and dispense were well covered in Brew Your Own’s May 97 issue and in the class handout for those alumni who attended more recent classes, so I will not dwell on the history, or the main brewing methods of the style. Instead I will attempt to provide a few hints on how to more closely replicate the British pub beer experience at home. The three day old, dried up, cheese and chutney sandwich you’ll have to manage on your own.

Malt

Farmers in England can still be persuaded to make the extra effort to grow top quality barley for brewing. British farmers work from a list of approved barley varieties and these varieties command a premium price over feed varieties. Barley varieties with exotic sounding names such as Maris Otter, Halcyon, Pipkin and, in Scotland, Golden Promise are as much a part of the recipe as a particular hop variety. They tend to be malted more slowly than American 2 row, resulting in less grain to grain variation. They are also kilned to a lower moisture content making them easier to mill with a 2 roller mill, easier to use in an infusion mash, less prone to sulphury flavors, stronger in flavour and darker in colour. As a commercial brewer, I have found that to get the best extract from an American 2 row malt you need a high mash temperature (156^oF). If you are using a single temperature infusion mash, then this precludes you from producing a highly fermentable wort and therefor a dry finishing beer. Using well-modified English malt will allow you to mash at a lower temperature, favoring fermentability, and still get a reasonably high extract. I have found that imported crystal malt seems to provide sweeter caramel flavors and colors with a reddish hue, compared to domestic caramel malt, which provides drier, spicier characters and a brown color. I have yet to brew with the new crystal malts from Great Western but the raw grains taste very good indeed.

Hops

British brewers use hops at a rate of about 1lb of medium a acid hops (4 -5%) per 43 gallon batch and mostly use whole flower hops. While the commercial English brewers have gone away from dry hopping over the years there’s no reason why American brewers need follow suit. Hops floating around the dispense container though, will seriously interfere with the dispense equipment, so containing the hop leaves in some kind of bag is recommended. Don’t obsess too much about sterility when dry hopping, partly because you can’t sterilize hops, but mainly because they act as their own preservative. It only takes about 7 days for a strong hop aroma to appear in the beer.

Fermentation

British brewers of cask beer have an advantage over their counterparts in this country in that they are able to devote an entire batch to cask conditioning rather than diverting a few kegs from a full batch destined to be filtered, carbonated and kegged. This makes it easier to arrest the fermentation with 1-2 specific gravity degrees still left and to remove the bulk of the yeast prior to conditioning. This means that American brewers will almost always have to prime their casks

Conditioning

A lot of articles on cask conditioning suggest adding a clarification aid such as isinglass as the beer is transferred to the cask. Commercial brewers in the UK now allow the yeast to remain in contact with the beer for the maturation phase and add finings only when the beer is required for shipping or dispense. This is because finings are very efficient at settling yeast to the bottom of the container and once there the yeast cannot do much fermenting. Some brewers even go to the trouble of rolling unfined, maturing casks in the warehouse occasionally, to keep yeast in suspension in contact with the beer. Cask beer is best drunk while it is young, but it should be easy enough to sample it regularly and judge for yourself.

Brewers who bottle condition already know that yeast, sealed up in a container with some sugars to ferment, will produce carbon dioxide gas. This gas cannot escape and so will dissolve in the beer causing the beer to become carbonated. The colder the beer the more CO₂ will dissolve but since the gas comes from fermentation and ale yeast cannot ferment much below 50^oF then there is a limit to the amount of carbonation that can be achieved without excessive pressure being generated.

Certain flavors, which may, or may not be appropriate in your beer, such as diacetyl (butterscotch flavor) or acetaldehyde (green apples) can only be removed by actively fermenting yeast. If the yeast is stuck on the bottom of the cask having been fined then it can do little to remove these flavors.

Since cask conditioned beer will be served without top pressure then only a low (0.9-1.2 volumes) level of carbonation is possible. That coupled with a slightly warmer serving temperature than keg beer, result in a greater perception of the multitude of flavors a cask beer can exhibit. Take into account using the flavorful barley varieties of English malt, dry hopping and natural clarification aided by finings, and you will see that the entire process is geared toward intensifying these flavors.

Clarification

The original article on cask conditioning did, unfortunately, contain a mistake. In the chapter titled Fining the author states that finings aid in the removal of proteins. This is not the case as finings such as isinglass and gelatin are only capable of causing yeast to sediment out more rapidly. British brewers shouldn’t have to worry too much about protein haze because British malt is low in protein and using kettle finings during the boil helps dramatically. Commercial brewers in the U.K. use an auxilliary fining agent for protein removal. Beers served at “cellar temperature of 50^oF are less likely to throw a “chill-haze.” The previous article also mentioned that isinglass is readily available and easy to use. Isinglass is very unstable at high temperatures and may lose all its activity if it is allowed to get too warm (over 70^oF). It will also only clarify the beer up to 4 or 5 times, so if the fined beer is moved around too many times it will not clarify. It is also possible to overfine resulting in a sediment that floats up a little off the bottom of the dispense container, and the same effect can occur if the finings are not extremely well mixed with the beer. If your finings comes with instructions that tell you to add them to boiling water then you are using porkine gelatin as a clarification aid. This has been known to upset the occasional vegetarian cask beer enthusiast.

Dispense

If you have fined the cask, and pressure has built up inside due to fermentation, the cask must be vented to atmospheric pressure before dispense. Do not suddenly release that pressure as the sediment will be roused up by the sudden release of gas and may not settle back down. If the sediment does get disturbed it is often a good idea to roll the cask, to remix the finings and yeast, and to allow it to completely resettle.

Some yeast can produce a lot of sulphur during the secondary fermentation, but that will collect in the headspace gas and can be vented away occasionally.

During dispense, if air is allowed to contact the beer then the container should be emptied in 2-3 days at the most. If you intend to keep the beer longer, then a blanket CO₂ pressure (¼ lb of pressure) will help preserve the beer’s freshness. Oxidation causes a loss of fresh hop aroma and a souring of the beer. The beer should not have a hint of vinegar, although that is a common character in English pub beers particularly during the summer.

If you decide to purchase a beer engine or handpump as they are sometimes called, then there are a couple of things to remember. They are designed to pull beer out of the cask but offer no resistance to forward flow. Any pressure in the cask will force beer forward through the pump without pulling on the handle, resulting in a huge mess, and a loss of beer. If the beer is carbonated to around 1.8-2.0 volumes of CO₂ then a sparkler attachment may be unnecessary. On most beer engines they are removable. Remember to rinse the pump out with water between tasting sessions, as beer left in the lines and pump can quickly ruin the system.