engleski

Effects of defoliation on antioxidative and antibacterial activity of grape skin extracts of Merlot and Blaufränkisch (Vitis vinifera L.)

Defoliation is a standard vineyard method with aim to achieve better ripening of grapes, breathability, better protection from various diseases like grey mold and better development of shoots. Process of defoliation can be implemented in different terms. The purpose of this study was to determine the effect of different terms of defoliation on antioxidative and antibacterial activity of grape skin ethanol extracts of Blaufränkisch and Merlot (Vitis vinifera L.). Total concentration of phenolic compounds, antioxidative activity and antibacterial activity on Gram-positive and Gram-negative human pathogens have been determined. The study was conducted on three treatments (control treatment – no defoliation, defoliation immediately after pre- bloom and defoliation before the start of veraison phase) and three repetitions. The results showed statistically significant enhancement of total phenolic compounds as well as antioxidative activity at both studied cultivars. Treatment of defoliation immediately after pre-bloom in the Blaufränkisch variety was more successful, resulted in higher concentrations of total phenols in grape skin extract compared to the defoliation treatment before the start of veraison phase. Treatment of defoliation immediately after pre- bloom in the Merlot variety was more successful than the treatment of defoliation before the start of veraison phase, resulted in significantly higher antioxidant activity of grape skin extracts. Antibacterial activity was increased only in extracts of Blaufränkisch.

defoliation ; Blaufränkisch ; Merlot ; antioxidative and antibacterial activity ; phenols

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