Mario Staver

Changes in physico-chemical and volatile aroma compound composition of Gewürztraminer wine as a result of late and ice harvest.

To investigate the changes in physico-chemical and aroma composition after late and ice harvest, Gewürztraminer wines were subjected to standard, enzymatic and GC/MS analysis. Late harvest (LHGW) and ice wines (IHGW) contained more sugars, extract and volatile acidity than standard wines (SGW). IHGW had elevated glycerol and gluconic acid amounts. LHGW was richer in monoterpenol oxides, β-damascenone, 1-octen-3-ol, acetates, ethyl cinnamate and 4-vinylguaiacol than SGW. IHGW contained even higher amounts, with increased citronellol, acetaldehyde, ethyl acetate, dicarboxylic acids esters, benzenoids, furans and acetals, and reduced fermentation aroma compounds. Based on odour activity values, the strongest odorants in SGW were fruity esters. In LHGW the impact of esters increased, while in IHGW cis-rose oxide, β-damascenone and 1,1-diethoxyethane emerged as the most potent. Fruity and sweet were the dominant aroma compound series in SGW and LHGW, but in IHGW declined, while terpenic, floral, chemical, pungent and ripe fruit aroma compound series increased.

Pre-fermentative cold maceration, saignée, and various thermal treatments as options for modulating volatile aroma and phenol profiles of red wine

The effects of six maceration treatments on volatile aroma and phenol composition of Teran red wine were studied: standard maceration (control C), cold pre-fermentation maceration (CPM), saignée (S), pre-fermentation heating with extended maceration (PHT) or juice fermentation (PHP), and post-fermentation heating (POH). PHP wine contained the highest amounts of esters, fatty acids and anthocyanins, and the lowest content of other phenols. Alternative treatments decreased higher alcohols in relation to control C. CPM treatment lowered the extraction of seed tannins, exhibited the highest acetaldehyde, ethyl acetate and C6-compounds levels, and had increased ester levels in relation to control C. POH wine contained the highest concentration of total phenols, flavonoids, monomeric, oligomeric and polymeric flavanols, and color intensity and hue. S and PHT wines contained lower amount of total phenols, but higher than in C and CPM wines. The calculated Odor Activity Values were used to establish significant differences between the treatments.