Prolonged ripening on the vine affects the polyphenolic profile of grapes and wine of 'Plavac Mali' (Vitis vinifera L)

摘要

Compositional differences in the polyphenolic profile and physicochemical parameters of grapes and corresponding wines of 'Plavac Mali' at five different harvest dates were evaluated by standard chemical analysis and high-performance liquid chromatography. Prolonged ripening enhanced the anthocyanin and flavonol concentration in skin tissue, with the exception of 3-O-glucosides of delphinidin, petunidin and quercetin, and 3-0-rutinoside of quercetin. Various trends in skin low-molecular-weight phenolic compounds were detected: increases in (+)-gallocatechin and (-)-epicatechin, and decreases in the others including (+)-catechin, (-)-epigallocatechin, and proanthocyanidins (Bl, B2, B3, B4). Grape seeds reached stable concentration of low-molecular-weight phenolic compounds at the third harvest date, while prolonged ripening had a significant influence on (-)-epicatechin and (-)-epigallocatechin. In contrast, in the corresponding wines, the concentrations of anthocyanins had two peaks - one at the third harvest date and one at the fifth harvest date - with no significant difference between the two, except in peonidin-3-O-glucoside. Prolonged ripening caused a production of wines with high concentration of (+)-gallocatechin and (-)-epicatechin, and the lowest concentration of (-)-epigallocatechin. The results indicate the potential of 'Plavac Mali' for prolonged grape ripening, but negative aspects of the prolonged ripening practice should also be considered.