Pyruvic acid and acetaldehyde production by different strains of Saccharomyces cerevisiae: relationship with Vitisin A and B formation in red wines.

The production of pyruvate and acetaldehyde by 10 strains of Saccharomyces cerevisiae was monitored during the fermentation of Vitis vinifera L. variety Tempranillo grape must to determine how these compounds might influence the formation of the pyroanthocyanins vitisin A and B (malvidin-3-O-glucoside-pyruvate acid and malvidin-3-O-glucoside-4 vinyl, respectively). Pyruvate and acetaldehyde production patterns were determined for each strain. Pyruvate production reached a maximum on day four of fermentation, while acetaldehyde production was at its peak in the final stages. The correlation between pyruvate production and vitisin A formation was especially strong (R (2) = 0.80) on day 4, when the greatest quantity of pyruvate was found in the medium. The correlation between acetaldehyde production and the formation of vitisin B was strongest (R (2) = 0.81) at the end of fermentation when the acetaldehyde content of the medium was at its highest. Identification and quantification experiments were performed by HPLC-DAD. The identification of the vitisins was confirmed by LC/ESI-MS.

Adsorption of anthocyanins by yeast cell walls during the fermentation of red wines.

This paper reports the anthocyanin adsorption profiles of the cell walls of different Saccharomyces strains isolated from grapes collected in the Spanish appellation controlée regions of La Rioja, Navarra, and Ribera del Duero. These strains are habitually used in red wine-making. The acyl derivatives of anthocyanins (acetyl and p-coumaryl compounds) were more strongly adsorbed than nonacyl derivatives. Peonidin-3G was also strongly adsorbed, as were its acyl derivatives. The greater presence of acetyl derivatives in the cell wall adsorbate leads to an increase in yellow color and a reduction in blue color with respect to the corresponding wine.