Production of whisky using specialty malts

Specialty malts are extensively used in brewing industry to enhance beer taste, mouthfeel and colour. Such malts are produced under conditions of high temperature, which results in non-enzymatic browning and an increased concentration of aromatic constituents, primarily through the action of Maillard chemistry. The majority of Scotch malt whisky is made using lightly kilned malted barley that yields only delicate aromas to the finished product. The characteristics differentiating whisky of one distillery from another is primarily introduced by varied distillation and maturation practices. With demand increasing for greater whisky variety, attention is turning to the utilisation of specialty malts. However, currently available specialty malts are produced primarily for brewing, and there exists comparatively little information regarding the impact of their use in distillation.

The present study investigated the impact of grain roasting conditions on malt quality characteristics, fermentability, and volatile composition of the distillate. Samples of commercial pot still malt were roasted at laboratory scale (following designed experimentation methodology) and assessed according to the Analytica EBC methods. SPME/GC-MS was used to evaluate the composition of malt volatiles, while a liquid-liquid extraction GC-MS method was developed to analyse the congeners in distillate.

The study highlighted the importance of grain roasting with regards to the number and concentration of heat-derived flavour-active volatiles present in malt and their carry-over into distilled spirit. The findings of this study have considerable implications for the commercial use of roasted malts in whisky production, and for the production of roasted malts for the distilling industry.