THE MANUFACTURE OF SCOTCH GRAIN WHISKY

Abstract

The special character of grain whisky distilled in Scotland depends on a number of factors. The conversion of the starch from cooked maize during the mashing process by the diastatic activity of barley malt is done in such a way that, besides a spectrum of soluble sugars, oligosaccharides and dextrins, some insoluble solids are also present. A significant proportion of initially unfermentable material becomes fermentable by a process of secondary conversion during the fermentation stage in the distillery. The fully fermented worts contain, besides ethanol, the higher alcohols, N-propanol, N-butanol, iso-butanol and iso-amyl alcohol, certain esters and aldehydes, and glycerol. After distillation in a Coffey still, the whisky contains higher alcohols, esters and aldehydes derived from the fermented worts. Lactic and acetic acids are also present as a result of fermentation by microbiological flora other than yeast. Among the changes in composition that take place during the maturing process are increases in the concentrations of esters, volatile acids and aldehydes.