Production

Cask Strength Malts

The tradition of high strength bottlings was a natural launch pad for cask strength malts,which have gathered momentum since the late 1980s. Ian Wisniewski finds out more.
By Ian Wisniewski
Cask strength bottlings vary from around 65% ABV, to just above the legal minimum of 40% ABV. Being bottled at the strength they reach in the cask (rather than being diluted with water to reach a particular strength), the appeal of cask strength malts is acquiring whisky in its most ‘natural’ form.Cask strength tends to be synonymous with single cask bottlings, and Glenrothes, for example, offers single cask bottlings at cask strength (whereas Glenrothes vintages are bottled at 43% ABV).“When we produce a single cask bottling it’s because we think of it as an unusual or idiosyncratic expression, as well as being outstanding. It has to be representative of the house style, as any vintage would, with ripe fruit, vanilla, citrus and spices, but there has to be something beyond that for us to consider it as a single cask bottling, and have released only nine such casks in 15 years,” says Ronnie Cox of The Glenrothes.Another option are small batch, limited edition releases, which, together with single cask bottlings, offer far more choice than the range of continually available cask strength options, such as Glengoyne 12 Years Old cask strength.A division between continually available expressions is that some have an established, unvarying alcoholic strength, while the strength of others varies from batch to batch.“Different batches of Benromach cask strength vary by around 1 to 2% ABV. We’re looking for the best possible casks to show the Benromach character, and if there’s a different strength or colour it’s not a problem, and we go with it.“For some consumers cask strength introduces the concept of subtle variation between batches, which they look forward to, and we give as much information as possible on this,” says Ewen Mackintosh of Gordon & MacPhail.A varying cask strength also entails practical considerations for the producer, in terms of packaging and administration.“You have to measure the strength while it’s in the bottle, you can’t do it based on the strength in the vat as there’s potential for it to change.“When bottling different batches at different strengths a smaller print run of labels is more expensive than a standard label, and there’s additional handling on the bottling line.“So from a stock control point of view it’s a new product.” says Ewen Mackintosh.Meanwhile, Glengoyne 12 year old cask strength is bottled at an unvarying strength of 57.2% ABV, having launched in September 2004.“The end result is well worth the hard work, but it’s quite a challenge to get consistent strength, flavour and colour, which we achieve by our chief blender vatting casks at different strengths, and getting the overall balance in the vat. We don’t use any caramel for colour and the whisky is unchill-filtered,” says Iain Weir of Ian Macleod.Another practical issue for distillers is that bottling at cask strength means smaller volumes, and a relatively higher retail price, which in turn reduces the potential number of consumers.Then again, limited-edition bottlings have a natural appeal for connoisseurs, with the retail price reflecting rarity.In addition to having an appeal in its own right, cask strength typically features on the ‘check list’ of desirable characteristics when connoisseurs choose more specialised malts.This also raises the question of whether cask strength is actually an essential element when bottling rarer malts.“It depends who it’s being aimed at.Connoisseurs often prefer cask strength, though in the birthday market for example, if someone is celebrating their 40th birthday by buying a 40 year old malt, then the strength is less relevant,” says Keir Sword of Royal Mile Whiskies.Another aspect of setting the bottling strength stems from the style of the malt, rather than any customer expectation.“We’d look at the style of whisky being bottled. Alight, delicate whisky is not a style that go’s well at a high strength, as the alcohol can overpower it,” says Ewen Mackintosh.Meanwhile, Highland Park 25 year old changed from being cask strength (which varied from 50-52% ABV) to a high-strength bottling, at the end of 2005.“As we had to keep changing labels it was quite problematic, particularly as we widened the number of markets, and decided to bottle it at a set strength of 48.1% ABV.“We did a lot of profiling and saw that it performs better at 48.1% ABV when enjoyed neat.We think it’s important to offer a high-strength malt that can be enjoyed neat.“This bottling strength also enables us to use fantastic casks that are under 50% ABV, and so which weren’t within the parameters of our cask strength bottling,” says Highland Park’s Jason Craig. This move brought Highland Park’s 25 Years Old in line with the 30 Years Old, also bottled at 48.1% ABV.The cask strength is determined by a combination of factors, including the original filling strength, the aging environment, and of course the length of aging.Filling barrels with new make spirit at 63.5% ABV is typical.New make spirit generally comes off the stills at around 70% ABV, adding water adjusts the strength.There have of course been exceptions, and the 1980s saw instances of filling strengths above and below this level, with some casks also filled at distillation strength during the 1970s.A practical reason for this was the continued growth in post-war production levels, until sales peaked in 1978, combined with a general shortage of barrels and limited warehouse space.As higher filling strengths comprise a higher proportion of alcohol to water, this can result in more alcohol-soluble flavour compounds such as fruit and wood components, and fewer watersoluble compounds being derived from the oak.Correspondingly, a lower filling strength and so relatively higher proportion of water, may see more water-soluble compounds being extracted, while also promoting oxidation.“Maturation will vary depending on the filling strength. Some tannins extract better into lower strengths than higher strengths, as some tannins are water-soluble and some are alcohol-soluble, so you get a different balance at different strengths.“In addition to the direct extraction from the cask, you also have the chemistry that’s happening in oxidation, which gives elegant top notes.“The activity of the wood is paramount, but oxidation and humidity also have an influence,” says Glenmorangie’s Rachel Barrie.The same malt will of course show a varying flavour profile at different strengths, so the bottling strength is a significant consideration; but then so is the strength at which the malt is sampled.“Our rare malt manager and chief blender take a view on what is the best strength to bottle our whiskies at, this is heavily dictated by finding the best strength to taste ratio.“I personally think it’s an enjoyable and educational experience to first try a high strength malt without water. Then try it with varying amounts of water to appreciate the dramatic taste change that can occur and to find the taste and character that best suits you,” says Iain Weir.A related consideration is that a cask strength malt will offer a different experience when diluted with water at home, compared to being diluted and reduced in strength by the distiller.“Because you’re adding water and consuming immediately it’s different to the distillery reducing and marrying the malt.“The water will be different, and marrying whisky with water takes a minimum of 10-14 days for us, compared to maybe five minutes in a glass when diluted by a consumer,” says Ewen Mackintosh.