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 biodegradatio n and, in particular, on the clarification processes. The pectolytic a ctivity in these yeasts was always lower than in filamentous fungi and certain bacteria. The effect of pectinases from these three biotic gr oups, as far as the viscosity was concerned, was not appreciable in ei ther 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 or iginating during primary fermentation from the unappropriate S. cerevi siae strain giving rise to thin lines. (C) 1997 Elsevier Science Ltd. All rights reserved.