Comparative profiling of small-sized phenolics throughout maturation in grape seeds of six Vitis vinifera L. red varieties grown under normalized ambient and viticultural conditions

Phenolic composition of Vitis vinifera grape berry seeds is greatly influenced by genetic background, edaphoclimatic factors and cultural practices. Berry seed phenolics are major determinants of wine quality and core of emerging nutraceutical products. Profiling berry seed phenolics has usually controlled for particular variables, thus producing valuable data that may not be generalizable. Studies involving series of influencing variables are desirable. This study characterizes at five maturation stages the phenolic composition of seed extracts from six world-wide distributed grape varieties grown in a single valley under common edaphoclimatic and cultural conditions. Quantitative intervarietal differences in particular phenolics at corresponding maturation stages and differential progression of varietal phenolic profiles throughout maturation were observed. Throughout maturation, most of monomeric, dimeric and trimeric flavan-3-ols showed somewhat similar declines, in striking contrast to the invariability of the B2 procyanidin dimer. These findings highlight the relevance of a broad comparative perspective for defining berry seed phenolic profiles.