engleski

Influence of pectolytic enzymes on the level of resveratrol in case of short maceration

The content of resveratrol in red wines depends on factors such as grape cultivar, geographical origin, fungi infections, sun exposition, wine type and wine-making procedures. The objective of this study was to determine the influence of pectolytic enzymes on the level and rate of 3, 5, 4’ -tri-hydroxystilbene (resveratrol) formation during fermentation in case of short maceration. The samples were derived from pure red grape varieties Babić and Plavina. The maceration periods in fermentation tanks were six days for Plavina, and 48 h for Babić. Changes in phenolic composition (total phenols, flavonoids, stilbenes) were monitored during six days. The presence of resveratrol monomers was analyzed by HPLC. Appearance of resveratrol monomers in Plavina and further fast increase in theirs ratio was recorded during the third day of the contact with grape skins which a generally known as the major source of stilbene compounds in wine. The dominant monomer was trans-resveratrol, while cis-isomer was present in significantly lower amounts. During the sixth day of fermentation no further increase in resveratrol concentration was noticed in Plavina variety, and even a slight decrease in trans-monomer concentration followed by increase in cis-monomer concentration was recorded. As opposed to this, Babić variety showed the continuous increase of resveratrol monomers content during the monitoring period of fermentation. In the case when the crushed grapes of Babić cv. were treated with pectolytic enzymes (Babić+PE), the final ratio of these stilbenes at the end of monitoring period was significantly higher in comparison to wine Plavina, and wine Babić produced without the addition of enzymes (4.6 mg/L of wine Babić+PE vs. 3.7 mg/L of wine Plavina vs 3.1 mg/L of wine Babić). The fact that maceration during Babić vinification lasted only 48 h, and that, in spite of such short maceration time, alcohol fermentation induced fast increase in resveratrol concentration even after separating the solid and liquid phase, implicates the conclusion that plant material does not contain free resveratrol monomers. This hence implies that resveratrol in grape is probably mainly present only in the bounded form. Alcohol fermentation induces degradation of derivatives and freeing of resveratrol monomers. The skin contact time is important for the extraction of resveratrol derivatives, but in case of short maceration time the addition of pectolytic enzymes can significantly increase the level of resveratrol monomers in wine.

Wine; Pectoliytic enzymes; Short maceration; Resveratrol

nije evidentirano