Acetaldehyde kinetics of enological yeast during alcoholic fermentation in grape must.

Acetaldehyde strongly binds to the wine preservative SO and, on average, causes 50-70 mg l of bound SO in red and white wines, respectively. Therefore, a reduction of bound and total SO concentrations necessitates knowledge of the factors that affect final acetaldehyde concentrations in wines. This study provides a comprehensive analysis of the acetaldehyde production and degradation kinetics of 26 yeast strains of oenological relevance during alcoholic fermentation in must under controlled anaerobic conditions. Saccharomyces cerevisiae and non-Saccharomyces strains displayed similar metabolic kinetics where acetaldehyde reached an initial peak value at the beginning of fermentations followed by partial reutilization. Quantitatively, the range of values obtained for non-Saccharomyces strains greatly exceeded the variability among the S. cerevisiae strains tested. Non-Saccharomyces strains of the species C. vini, H. anomala, H. uvarum, and M. pulcherrima led to low acetaldehyde residues (<10 mg l), while C. stellata, Z. bailii, and, especially, a S. pombe strain led to large residues (24-48 mg l). Acetaldehyde residues in S. cerevisiae cultures were intermediate and less dispersed (14-34 mg l). Addition of SO to Chardonnay must triggered significant increases in acetaldehyde formation and residual acetaldehyde. On average, 0.33 mg of residual acetaldehyde remained per mg of SO added to must, corresponding to an increase of 0.47 mg of bound SO per mg of SO added. This research demonstrates that certain non-Saccharomyces strains display acetaldehyde kinetics that would be suitable to reduce residual acetaldehyde, and hence, bound-SO levels in grape wines. The acetaldehyde formation potential may be included as strain selection argument in view of reducing preservative SO concentrations.