Whisky Magazine Issue 82
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In the first of two articles on yeast, Ian Wisniewski looks at the range available to distillers,and the practicalities that different choices entail.
Yeast may be a minor factor in terms of production costs, but its contribution to the production process is far more significant. Converting sugars into alcohol is a vital though practical role, while producing various flavours during fermentation is more creative.
And with brewer's yeast now largely absent from the industry, the focus is on distiller's yeast.
“Distiller's yeast tends to be grown on molasses, and it takes about three weeks to have the finished product, which includes two weeks to culture the yeast in the lab,”says Grant MacKenzie of Kerry Ingredients and Flavours, a leading yeast supplier which is part of the Kerry Group.
Distiller's yeast is available as creamed yeast (also known as liquid yeast), pressed yeast (also referred to as caked yeast),and dried yeast.
“Creamed yeast is around 20 per cent dry matter and behaves like a liquid. At 23 to 24 per cent dry matter you start to get a paste,and at 28 per cent dry substance you have a cake, with pressed yeast having about 28 per cent dry matter. You need relatively more creamed yeast compared to pressed, but it's only a very small amount,”says John Ross of Wm Grant & Sons.
Individual strains of yeast are also available in different formats.
“We offer five strains of distiller's yeast, the classic is M,dating from the mid 1960s. We believe, since then it's made more Scotch whisky than any other yeast. We also offer MX,which has been available for about 25 years, as well as MS-1, SAForte and M+....