Whisky Magazine Issue 35
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Ian Wisniewski takes us step by step through the mashing process
With distillation and maturation seen as the key partnership influencing the flavour of malt whisky, it's easy to dismiss mashing as an ‘industrial equation.' Starch equals sugar, which in turn equals the yield of alcohol. However, as every stage of the production process plays a vital role in maintaining consistency, any discrepancies during mashing can also have a significant effect on fermentation, and therefore the end result.
A prerequisite for successful mashing is milling the barley, with each distillery having an established ‘tech spec.' Milling is undertaken using two sets of rollers, the first squeezes the grains to ‘pop' the husk, with the second set grinding the kernels further.
This yields three separate grades of malt: husk, grits (also known as middles) which are medium-ground, and the finer-ground fines (or flour). Collectively termed grist, a typical specification is around 20 per cent husk, 70 per cent grits and 10 per cent flour.
This ratio provides an ideal total surface area, promoting a maximum rate of conversion from starch to sugar during mashing (when grist is combined with 3-4 batches of progressively hotter water in a mash tun).
The proportions of each grade also reflect practical considerations, that balance maximum extraction with good drainage. Husks help water drain through the grist, though too much husk would prevent the grist from mashing properly. Similarly, too high a level of fines could result in an enormous helping of porridge...