A cask breather, sometimes called an “aspirator,” is a demand valve used in conjunction with a beer engine and a carbon dioxide tank for the dispense of cask-conditioned beers. It allows beer drawn from the cask to be replaced with the equivalent amount of sterile gas at atmospheric pressure.The objective is to extend the shelf-life of the beer by preventing outside air from coming into contact with it. If set up correctly, no CO2 should become dissolved in the beer, which thus should not become in any sense gassy. Tastings set up by CAMRA’s Technical Committee have repeatedly demonstrated that people are unable to tell the difference between beer stored under a cask breather, and that without.
However, on more than one occasion, CAMRA’s National AGM has rejected giving any approval to the device. Some of the objections seem spurious, such as arguing that the flavour actually benefits from exposure to the atmosphere after the cask has been tapped. It all seems to boil down to a generalised dislike of CO2 in any form, and a suspicion that sanctioning the use of breathers will represent the thin end of the wedge.
A cask breather should only really be necessary for pubs without sufficient trade to empty a cask within three days. Clearly, beer stored under a breather will be much preferable to either no beer at all, keg beer, or rancid cask beer. In ideal conditions, there should be no need for it if the pub can shift its beer quickly enough, but in the real world that is often not the case. The objection is a case of the best being the enemy of the good.
One concern, though, is that if CAMRA gave the green light to cask breathers, some pubs might take it as an encouragement to use them to further increase an already over-extended beer range. If a cask will last seven days rather than three, then you can have twice as many different beers on. However, while a seven-day-old cask under a breather will be far better than one exposed to the atmosphere, it’s still going to have a touch of staleness about it, and not be a patch on one that’s just been tapped. There used to be one local pub that I suspected of routinely using cask breathers, and all its beers, while drinkable enough, tasted as though a damp cloth had been thrown over them to dial down their flavour.
Some breweries have found their pubs effectively excluded from the Good Beer Guide because it has become known that they recommend licensees use a cask breather as a matter of policy. However, realistically very few GBG pubs receive a cellar inspection, and so plenty, especially independent free houses, must end up being listed even though they use the devices. So it makes sense for CAMRA’s revitalisation proposals to include the recommendation that “CAMRA should adopt a neutral position on the use of cask breathers,” neither condemning nor explicitly approving them. If the beer’s good enough, a pub will be listed; if it isn’t, it won’t be.