Effects of time of grape pomace fermentation and distillation cuts on the chemical composition of grape marcs

The effects of fermentation time and distillation cuts on the composition o f distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol. 3-methyl-1 -butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate. 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hex enol. cis-3-hexenol, 2-phenylethanol. ethyl butyrate, ethyl hexanoate, ethy l octanoate, ethyl decanoate. ethyl dobecanoate, 2-methylpropanoic acid, 3- methylbutanoic acid. hexanoic acid, octanoic acid, decanoic acid, and dodec anoic acid were assessed through data generated according to a factorial de sign using analysis of variance and principal component analysis. Four time s of storage of pomace obtained following wine-making of two grape varietie s of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered: volatile compounds in the 24 samples generated were analyz ed directly, and indirectly after extraction and concentration, by capillar y gas chromatography. The results generated have suggested clear difference s (P < 0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distil late fractions analyzed were accounted for by the contents of diethyl butan oate. ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-meth ylpropanoic acids for Loureiro. whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic aci ds for Alvarinho.