Abstract
Welschriesling is a variety common to Central and Eastern European wine-producing countries; however, its aromatic composition remains poorly understood. Our study aims to determine the volatile profile of Welschriesling by analysing varietal thiols, esters, higher alcohols and monoterpene alcohols in commercial wines. In addition, the selection of commercial yeast starters and lactic acid bacteria (LAB) was used to modulate Welschriesling wine volatile composition. Both the selection of yeast and LAB had a significant impact on the compositional parameters of the wines. Yeast starter Uvaferm 228 (UVF228) was the most effective in terms of 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) production. For the ethyl esters of fatty acids (EEFAs), higher alcohol acetates (HAAs) and higher alcohols (HAs), no common inter-group behaviour could be observed based on yeast selection, however, as a group, EEFAs and HAs were highest in wines fermented with UVF228.Malolactic fermentation (MLF) significantly influenced varietal thiols, irrespective of the LAB strain used. Concentrations of 3MH significantly increased with MLF, 4-mercapto-4-methyl-pentan-2-one (4MMP) concentrations decreased, while 3MHA concentrations remained unaltered. This study showed the specific influence of yeast and LAB strain on selected volatile compounds. MLF appeared to be a promising tool to boost the presence of 3MH in wines, however, the results need further confirmation across a range of fermentation conditions and strain selections.
Highlights
Wine fermentation is a complex microbiological process in which yeast plays a fundamental role (Padilla et al, 2016)
For the ethyl esters of fatty acids (EEFAs), higher alcohol acetates (HAAs) and higher alcohols (HAs), no common inter-group behaviour could be observed based on yeast selection, as a group, EEFAs and HAs were highest in wines fermented with Uvaferm 228 (UVF228)
Commercial Welschriesling wines were screened for 28 volatiles, deriving from fermentation, as well as for varietal thiols and four monoterpene alcohols
Summary
Wine fermentation is a complex microbiological process in which yeast plays a fundamental role (Padilla et al, 2016). Yeasts play an essential role in tailoring wine aroma by releasing volatiles from non-volatile precursors or de novo synthesis from amino acids, lipids and other nutrients found in must (Swiegers et al, 2005). Amino acids, significantly influence the production of varietal thiols as well as the 3-mercaptohexyl acetate (3MHA)/3MH acetylation rate (Pinu et al, 2014), while yeast strains differ in their ability to release varietal thiols from their respective precursors (Dubourdieu et al, 2006; Swiegers et al, 2007; Jenko et al, 2013). The ability of 82 different yeast strains to release varietal thiols from synthetic must differed 20-fold for 3MH and 35-fold for
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