Grape pectic enzyme treatment effect on white musts & wines composition

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