It all comes out in the wash

It all comes out in the wash

Every part of the distillation process is crucial to making good whisky. Ian Wisniewski explains

Production | 21 Jul 2006 | Issue 57 | By Ian Wisniewski

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With the character of the new make spirit being a focal point of distillation, it’s tempting to assume that the low wines are simply an interim stage.But if the low wines didn’t comprise the right parameters to be refined by a second distillation, the new make spirit wouldn’t attain a consistent character and quality. Nor can spirit stills correct anything ‘untoward’ in the low wines.“I think the wash distillation is a much undervalued part of the process,” says Douglas Murray of Diageo.“The wash still conditions everything so that the spirit still works. If you don’t have the right flavour potential in the low wines you won’t get the character you want in the new make.There are some compounds you don’t want and it can take two distillations to deal with them.” But then again, reaching the right specification after the first distillation is equally dependent on a successful fermentation.“Wash is fermented at a specific gravity, all distilleries are a bit different, this determines the alcoholic strength which has quite a bearing on distillation, says William Grant’s John Ross.“If we change the original gravity this alters the alcoholic strength of the wash, which changes the strength and flavour profile of the low wines.” As there are no ‘cut points’ during the first distillation, it’s a case of collecting low wines until the strength reaches around 1% ABV. This may make it seem simpler than managing the spirit cut during the second distillation, but there’s plenty of action in the wash still.“The wash has the greatest number of different compounds, with the residue yeast still present, together with some residual sugars and proteins, so a lot more happens in the wash still in terms of the range of compounds reacting together,” says Glenmorangie’s Rachel Barrie.With so much happening in the wash still it may seem surprising that the low wines are not routinely assessed, which makes it even more interesting to know what they can offer.“Benromach’s low wines are clean and estery with rich fruitiness and a waxy oiliness at the start then as the distillation continues it moves to a peaty character, roasted malt and toasted cereal starts to build up,” says Gordon & MacPhail’s Ewen Mackintosh.“The oily theme is constant all the way through, eventually moving onto more pungent notes. The peak for peatyness seems to be in the middle.” With a strength of around 20-25 per cent, low wines generally represent around 30-40 per cent of the original volume of wash.“The origin of the term ‘low wines,’ reflects them being half-way between water and spirit. They were originally termed low grade wines, and then abbreviated to low wines, always in the plural,” explains Chivas Brothers’ Alan Winchester.Knowing that stills of a certain size and shape have a particular influence on the distillate is only one aspect of a complex (and not always fully understood) equation, with the heating method and rate of distillation also determining factors.Stills with taller, narrower necks promote lighter, more delicate notes, as the taller the still the greater the degree of ‘reflux.’ This is because heavier, denser, oilier flavour compounds have a higher boiling point than lighter flavour compounds, and as they rise up the still the temperature becomes relatively cooler, causing them to condense and begin their descent back towards where they started.However, the heat of rising vapours will also result in some of this condensate revapourising before reaching the boil pot (base), and beginning a return journey back up the neck of the still.A still with a shorter, wider neck means less temperature variation, and consequently less reflux. This promotes the progress of heavier flavour compounds into the condenser, yielding a fuller-bodied distillate.But neck-size is only one factor, as reflux can be increased by adding strategic design features such as a boil bowl (bulbous section between the boil pot and neck). When vapours carrying heavier flavour compounds expand into this larger, relatively cooler area, they condense and return to the boil pot. The level of reflux also depends on the shape of the boil bowl, the more acutely convex it is, the more reflux it promotes.Meanwhile, the degree of reflux is also influenced by the heating regime. Gentler heating means a slower rate of distillation, more reflux, and a lighter distillate. Heating the still more rapidly increases the rate of distillation, driving off vapours more readily, and reducing the degree of reflux, which promotes a higher proportion of heavier flavour compounds.“The method or level of heating can be more influential in the wash still than the spirit still. A greater level of heating (eg. with directly fired stills) can promote sulphury, cereal character. A gentler, slower distillation will promote a lighter and more estery character,” says Rachel Barrie.Trying to quantify the influence of different aspects raises the question of how influential the heating method can be on the character of the distillate, compared to the shape of the still.“The influence of the size and shape of the still is much greater than differences in heating. Heating method accounts for about 20-30 per cent of the character of the low wines, with the size and shape of the still accounting for a significantly higher percentage,” says Rachel Barrie.Steam-heated coils or pans, also known as kettles, are generally considered to provide the best heat control. It was in the 1960s-70s that indirect heat (using steam) largely replaced the traditional method of direct heating (using a coal fire or gas flame), which is still used at distilleries such as Glenfiddich and Glenfarclas.Using direct heating also entails using rummagers in the wash stills, essentially lengths of copper ‘chain mail’ mobilised by motorised arms, and dragged across the base of the still to remove any solids which may lodge there.“Glenfiddich uses gas heating for all the stills, with rummagers to avoid baking on any solids, which are mostly yeast (containing 40-50 per cent protein, and a source of some sulphur compounds). The rummager is copper but as it’s in contact with liquid this is not significant, the cleaning effect of copper is in the vapour stage,” says John Ross.At Glenfarclas the rummagers were originally powered by a water wheel in the 1800s, which remains on site though in a different area.“The wash still rummagers are now run by mechanical motors with a gearbox, the copper chains are about 10 meters long in total. Each chain is about 30 cms wide with chain links around the size of an old penny.They go round very slowly covering the base of the still and around 1.5 meters up the side, though you still get a little caramelisation coming through as toffee and fudge notes in the mature spirit, and part of this is down to distillation,” says Ian McWilliam of Glenfarclas.“The chain is scraping the interior surface, following the same route each time, which leaves the base of the still very shiny and with a few small ridges, although the rummagers are made from a softer compound of copper than the stills. This means the life of the still is considerably less than when using steam coils, particularly the combined effect of the rummager and using direct fire,” adds Ian McWilliam.The level of solids within the wash also means that a far more rigorous cleaning regime is required for wash stills , as there is a risk of material building up on the base of the still, if using direct heat, or on the coils and pans (kettles) if using indirect heat. But the risk of any ‘baked on’ material affecting consistency isn’t the only consideration.“If the wash stills aren’t cleaned properly they become inefficient as you loose on heat transfer and slow down the distillation.Wash stills can be cleaned automatically, and using an integrated cleaning system to comply with health and safety regulations is now the norm,” says Alan Winchester.
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