Fermentation by-products. By products produced during wine fermentation in mixed culture (▲ dashed lines), in S. cerevisiae pure culture (♦continuous lines) and in immobilized S. bombicola pure culture (○ continuous lines). Production of (a) acetaldehyde, (b) ethyl acetate, (c) propanol, (d) acetoin and (e) amylic alcohols. The data represented are the mean of the three technical repetitions for two independent biological samples ± SD. Values displaying asterisk are significantly different according to the Duncan test (0.05%).