Grape juice biodegradation by polygalacturonases from Saccharomyces cerevisiae

Some strains of S. cerevisiae capable of degrading pectic susbstances were selected in order to determine their effect on must biodegradation and, in particular, on the clarification processes. The pectolytic activity in these yeasts was always lower than in filamentous fungi and certain bacteria. The effect of pectinases from these three biotic groups, as far as the viscosity was concerned, was not appreciable in either case; however, a relevant effect, caused by enzymes from yeasts, on filtration time was found. With strains 1389 and C6, the filtration time was reduced by about 50%. It is concluded that biodeterioration of must/wine may be caused by an excess of yeast polygalacturonases originating during primary fermentation from the unappropriate S. cerevisiae strain giving rise to thin lines. (C) 1997 Elsevier Science Ltd. All rights reserved.