GRAPE PECTIC ENZYME TREATMENT EFFECT ON WHITE MUSTS AND WINES COMPOSITION

White grapes of three different cultivars ('Macabeo', 'Xarel.lo' and ' Parellada') were treated with the same commercial pectic enzyme prepar ation on an industrial scale. The effect of this treatment on must and wine composition was studied in three consecutive years (1991, 1992 a nd 1993). Twenty-one parameters were determined to evaluate effects of the pecticenzyme treatment. Turbidity, galacturonic acid, total and a cid polysaccharides, total and nonflavonoid phenols, proteins and meth anol were affected by the treatments, although this effect usually dep ended on the cultivar and/or year. Moreover, the effects of treatment were more marked in must than in wines. However, a considerable loss o f glucosidic colloids was found on musts and wines from treated grapes . The loss of must polysaccharides depended on their initial content a nd were mainly due to the pectin losses. Pectin lysis was responsible for increases in galacturonic acid levels which could be used as an in dex in wines (within a cultivar and year) to indicate pectic enzyme tr eatment.