Influence of oak wood chips–grape mix maceration on the extraction of anthocyanins from low-extractable anthocyanin content red grapes

Wine color depends not only on the amount of anthocyanin present in the grapes, but also on the amount of them that may be extracted from grapes and their interactions with other phenolic compounds. Color stabilization is also specially important in poor color wines. The main goal of this study was to evaluate the effect of the addition of oak wood chips on the extractability of anthocyanins from homogeneous grapes which were previously classified by hyperspectral image analysis. Ten Vitis vinifera L. cv. Syrah grape skins from grapes previously classified as low-extractable anthocyanin content by hyperspectral image analysis were underwent to simulated maceration in wine-like solution, with or without French oak (Quercus petraea L.) wood light-toasted chips. For each sample, anthocyanin composition of the extracts was measured at the third day of maceration by HPLC chromatographic analysis and after that the obtained data were submitted to chemometric analysis. The presence of oak wood chips in the extraction media did not cause significant changes on the anthocyanin extractability for all samples in the aforesaid homogeneous created group. The use of this technique might allow wine producers obtaining red wines that may present high color quality and stability due to the copigmentation and color preservation procedure. Hyperspectral image analysis was a crucial non-destructive tool in this study that allows to sort the berries and then use the same samples for other destructive analyses such as the evaluation of influence of oak chips–grape mix maceration on the anthocyanin extraction from grape skins.