Scientific Bulletin of the Technical University of Lodz

Formation of by-products during alcoholic fermentation is a complex process. Particular attention should be paid to generation of higher alcohols because of its complex mechanism and dynamics. In XIX century the higher alcohols were thought about as “bacterial metabolites of spoilage” that contaminate alcoholic beverages. At the beginning of XX century Ehrlich proved that these compounds were produced by yeast from amino acids and they naturally occurred in all alcoholic beverages derived from spirits of agricultural origin. The quantity and profile of fusel alcohols in the wash depend on many factors such as raw materials used to prepare the sweet mash, yeast strain and the inoculum dose, supplements added to the mash. Investigations of many researchers prove that higher alcohols are formed through catabolic and anabolic pathways. They are either products of amino acid catabolism – as was found by Ehrlich or by-products of amino acid synthesis from pyruvate through the anabolic pathway. The occurrence of fusel alcohols in raw spirits from agricultural distilleries is a result of the presence of amino acids, sugars and products of their metabolism mainly aldehydes, in fermented mashes.