Quantification of key odor-active compounds of a novel nonalcoholic beverage produced by fermentation of wort by shiitake (Lentinula edodes) and aroma genesis studies

A novel non-alcoholic beverage was produced by fermentation of wort with shiitake (Lentinula edodes), and the key aroma compounds were quantified. Reconstitution studies confirmed their contribution to the overall aroma of the beverage. Kinetic studies indicated that shiitake synthesized the key odor-active compounds imparting fruity and rose-like odors, while the typical odorants of the substrate wort were degraded during the fermentation. By means of the standard addition method, a good linearity (R-2 >= 0.983) and degree of precision (RSD < 13%) were obtained for quantification of twelve aroma compounds. Their respective odor activity values (OAVs) were calculated to estimate their contribution to the overall aroma. Methyl 2-methylbutanoate, produced by shiitake, showed the highest OAV (30) and was responsible for the typical fruity odor of the beverage. A correlation between the concentration of methyl 2-methylbutanoate and the perceived fruitiness of the beverage was observed. The biosynthesis of this methyl ester by transformation of 2-methylbutanoic acid and L-isoleucine was confirmed by means of an isotopic labeling experiment. (C) 2015 Elsevier Ltd. All rights reserved.