The
nitrogen composition of wines aged with yeast for a long period of time, as in the case of sparkling wines, depends on the composition of the base wine and on the compounds released by the yeast. In this paper, the release of the different classes of
nitrogen compounds during
autolysis of one of the strains of yeast used in the manufacture of sparkling wines has been studied. The yeast, Saccharomyces bayanus, was suspended in a model wine
buffer, pH 3.0 and 10%
ethanol, and incubated at 30 degrees C. Samples of the autolysate were taken after 4, 24, 48, 72, 168, and 360 h of
autolysis. An electrophoretic and chromatographic study was conducted of the
proteins,
peptides with molecular weights higher and lower than 700 Da, and
amino acids released during the
autolysis. Using SDS-PAGE, it was observed that it was predominantly
polypeptides with molecular weights lower than 10 000 that were released. Through HPLC of the fraction lower than 10 000 Da, it was observed that it is
polypeptides with molecular weights of between 10 000 and 700 Da that are released first and that these later break up to give rise to
peptides with molecular weights lower than 700 Da, which in turn break down into
amino acids. This indicates that the nature of the
nitrogen compounds present in wines aged with yeast depends on the aging time, being less polymerized as the aging time increases.