Effect of Grist Particle Size Distribution and Wort Turbidity on Ester Composition of Malt Whisky New Make Spirit

The parameters used during milling of malt have considerable implications for the turbidity of wort collected during lautering, and wort turbidity has previously been demonstrated to impact ester development by yeast (during fermentation of brewer's wort). The present research assesses the impact of milling regime and wort turbidity on congener development during production of malt whisky new make spirit. New make spirit was produced from pot still malt prepared with a disc mill under differing milling regimes (mill gap: 0.5–1.5 mm; laboratory scale). Use of increasingly coarse milling conditions positively correlated with wort turbidity and reduced concentration of acetate and ethyl esters in new-make spirit. Similar to previous research within the brewing industry, turbid wort was generally associated with reduced ester content, particularly in samples produced under the coarsest milling conditions (mill gap: 1.5 mm). Turbidity of new-make spirit (diluted to 30% ABV) was reduced in samples produced from wort of elevated turbidity, likely due to reduced content of ethyl esters and other haze-active congeners.