Vladimir Jukić

Effects of early leaf removal on grape yield, chemical characteristics, and antioxidant activity of grape variety Cabernet Sauvignon and wine from eastern Croatia

ABSTRACT The aim of this study was to determine the impact of two different treatments of early defoliation performed before blooming on: grape yield, chemical parameters, polyphenols content, and antioxidant activity of grape and red wine cv. Cabernet Sauvignon from the vineyard located in Ilok, the eastern continental region of Croatia. Two different treatments of leaf removal (LR) were performed: removal of 3 leafs (T1) and 6 leafs (T2) before blooming, together with control (no leaf removal) (T3) during two years (2013 and 2014). Crop yield and average cluster weights per vine were determined. Density, pH and titratable acidity were measured in must, while the total phenols, total anthocyanins and antioxidant activity were measured in the extract of grape skin and produced wine. The analysis of individual anthocyanins in wine was performed by HPLC method. T2 treatment significantly lowered the crop yield and the average cluster weights, and increased total phenols, total anthocyanins, antioxidant activity and most abundant individual anthocyanins in wine. Defoliation did not affect the other chemical parameters in must, grape skin extract and wine. Vintage year is statistically the most significant source of variability for density of must, antioxidant activity in grape skin extract, as well as pH and titratable acidity in wine. This study has showed that the early leaf removal treatment in eastern continental part of Croatia could be used for the production of smaller quantity of high quality Cabernet Sauvignon red wine abundant with anthocyanins.

Effects of early leaf removal on volatile compounds concentrations in Cabernet Sauvignon wines from the Ilok vineyards

The aim of this two year study was to evaluate effects of basal leaf removal before blooming on volatile composition of Cabernet Sauvignon wines in the Ilok vineyards (eastern Croatia). During two consecutive vintages (2013, 2014), two different treatments of basal leaf removal were applied: removal of 3 and 6 leaves, and control without leaf removal. Volatile compounds of resulting wines were identified and quantified by gas chromatography coupled with mass spectrometry. Organic acids and higher alcohols remained unaffected by treatments of early defoliation wine, except acetic acid and 2-methyl-6-hepten-1-ol. Early leaf removal was affected on six esters concentration only in the 2014 with different outcome. For compounds unaffected by defoliation, vintage was statistically significant source of variability, as the results of multivariate analysis have confirmed. Defoliation treatments in Cabernet Sauvignon wines from eastern continental part of Croatia should be adjusted to the weather condition in growing season.