Leaf removal applied at the pea-size stage of berry development in a season characterized by abundant rainfall improves both the chemical composition and sensory quality of Istrian Malvasia wine, even when performed by machine, implying that this technique might be successfully applied in large-scale viticultural production. © 2018 Society of Chemical Industry.

Grapes from the Vitis vinifera (L.) varieties Ribolla Gialla and Malvasia Istriana were subjected to two skin contact procedures: pomace maceration and whole berry maceration during alcoholic fermentation. Wine free volatile compounds were determined using two extraction techniques coupled to GC; odour activity values were calculated and compared to control wines without skin contact. The highest concentrations of esters and relative fruity impacts were determined in the control wines for both varieties. Pomace maceration was found to be an effective procedure for the extraction of varietal aroma compounds like terpenes, but only in the Malvasia Istriana was their higher impact on floral odour determined. Pomace maceration resulted in higher total phenol and methanol content. Whole berry maceration was less efficient in terpene extraction, and its impact on general wine composition was not so radical. Control wines were chosen as preferred wines for odour and overall impression.

Zelen, Ribolla Gialla and Malvasia Istriana, grapes from the Vitis vinifera (L.) varieties, were subjected to four processes involving grape skin contact. Fresh and fruity young wines were produced by adding 6% or 12% grape berries, respectively, during alcoholic fermentation, freezing the pomace (Fp) and the freezing whole grapes (Fg). Wine-free volatile aromatic compounds were determined using two extraction techniques coupled to gas chromatography (GC). These aromatic compounds and wine standard chemical parameters were compared to control wines produced without skin contact. Esters, higher alcohols, terpenes, volatile phenols and C 6 alcohols proved to be the most important sensorial odorants in wines. Both the content of aromatic compounds and the odour activity values showed some positive effects from skin contact. The freezing of the grapes and addition of 12% grape berries proved most effective for Zelen and Malvasia Istriana, producing a more intensive fruity and floral odour, a less intensive solvent odour and additional freshness. The same processes resulted only in additional fruitiness or a less intensive solvent odour in Ribolla Gialla while the lowest concentrations of grape derived terpenes were achieved for this variety. The three varieties were most affected by freezing processes. During the sensorial evaluation, the wines that had been subjected to skin contact were generally preferred to the control wines.

Wine aroma is influenced by a number of volatile compounds. This article describes the validation of the method for 26 volatile compounds found in wine. Volatile compounds were determined with discontinuous liquid-liquid extraction and GC-MS detection. It was determined, that the method is linear with square correlation coefficient ranging from 0.961 to 0.999. Limits of quantitative determination range from 0.52 μg/L to 14.8 μg/L. Recoveries range from 71.1% to 105.7% except for two compounds with lower recoveries. Measurement uncertainty ranges from 5.0% to 28.9%. According to the validation, the method is suitable for the determination of at least 24 volatile compounds common to wine. A practical method application was presented on Zelen wine variety from two different production procedures. Ključne besede: vino, aroma, hlapne spojine, GC-MS Prispevek je del doktorske disertacije z naslovom "Vpliv maceracije na aromatične značilnosti primorskih belih vin", mentorica prof. dr. Tatjana Košmerl

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