Conventional and enzyme-assisted autolysis during ageing over lees in red wines: Influence on the release of polysaccharides from yeast cell walls and on wine monomeric anthocyanin content

HPLC with refractive index detection (HPLC/RI) was used to study the autolytic release of polysaccharides from the cell walls of six strains of Saccharomyces cerevisiae and the commercial yeast species Sacch. uvarum in a model medium over a nine month period of ageing over lees. The effect of adding β-glucanase was also studied. In the presence of this enzyme autolysis was complete within 2–3 weeks; conventional autolysis needed to proceed for at least five months before large quantities of released polysaccharides could be detected. The final polysaccharide profile of the model medium obtained by enzyme-assisted autolysis was, however, different to that obtained by conventional autolysis, with more fragments of smaller molecular weight and a greater grouping of molecular sizes in the HPLC/RI peaks. The influence on the monomeric anthocyanin content of commercial red wines was examined by HPLC with photodiode array detection (HPLC/PDAD). Ageing over lees without enzymes appeared to have a protective effect on the total monomeric anthocyanin content, while the use of β-glucanase led to a large reduction in their concentration, probably via the undesirable activity of β-glucosidase impurities.