Effect of defoliation process on Aglianico grapes and wine characteristic

The main of master thesis was to identify and evaluate the influence of early defoliation on the concentrate of polyphenols and volatile compounds in grapes and wine from which leaves were removed at different points: south (D-S), north (D-N), north-south (D-NS). Defoliation increased the concentration of polyphenols, antioxidant activity and colour intensity, especially in D-NS sample where defoliation was performed on both sides. In D-NS sample the total of polyphenols was 2755±11 mg l-1 and the antioxidant activity was 18595±108 TEAC μmol l-1. 14 different anthocyanins were identified in grapes and wine samples. The highest concentration anthocyanin in both grapes and wine were found Malvidin-3-O-glucoside (Mv). In control sample of grapes Mv was 70% of total anthocyanins, 60% in D-S sample and 56% in D-N and D-NS samples. In control and D-N wine samples Mv was 69% of the total anthocyanins 65% in D-S wine sample and 68% in D-NS wine sample. The results of anthocyanins in grapes and wine showed that the most effective defoliation was after removal of leaves from the southern side (D-S). The largest group of volatile compounds in grapes was aldehydes. In control sample aldehydes accounted for 90% of the total volatile compounds, 60% in D-S and D-N samples and 69% in D-NS sample. Control sample had the highest concentration of aldehydes (1420.76±423.46 ng ml-1). The highest concentration of aldehyde in grapes was 2-hexanal, and the highest content was found in control sample (1282.57±1476.37 ng ml-1). Esters were the largest class of volatile compound in wine. The highest content of esters was found in D-NS wine sample (505.9±68.9 ng ml-1) and was 15% higher than control wine. Alcohols were the highest concentration of compounds in wine and accounted for 90% of the total amount of volatile compounds in all samples: C (93%), D-S (90%, D-N (90%), D-NS (88%). The results also showed a strong decrease in ethanol, 1-butanol-3 methyl, and phenylethyl in defoliated samples compared to the control. Control sample showed the highest amount of total alcohols (6536.0±1386.5 ng ml-1