Volatile by‐products formed in batch alcoholic fermentations: Effect of y‐alum1na and kissiris supported biocatalysts

Abstract The formation of acetaldehyde, ethyl acetate, propanol‐1, 2‐methyl‐propanol‐1, 2‐methyl‐butanol‐1, 3‐methyl‐butanol‐1 in repeated batch alcoholic fermentations of raisin extract by Immobilized Saccharomyces cerevisiae on mineral supports y‐alumina and kissiris was mainly studied. It was found that the fine aroma appeared in the products obtained by the fermentations performed by y‐alum1na supported b1ocatalysts, is attributed to the reduction of the concentration of amyl alcohols, total volatiles determined as well as in the increase of ethyl acetate. Kissiris supported biocatalyst increases the concentrations of volatiles determined. Furthermore, the effect of y‐alumina pellets on volatiles formed in its presence as promoting material at molasse fermentations is also reported. Finally, the formation of volatiles in raisin extract alcoholic fermentations, in comparison with those obtained in sugar beet molasse was examined.