Relationship between skin break force and anthocyanin extractability at different ripening stages

The extractability of anthocyanins from winegrapes with different skin hardness at two different ripening stages was evaluated. Skin hardness was assessed by texture analysis, a rapid and low-cost analytical technique. Grape berries of cv. Brachetto were calibrated according to their density estimated by flotation in 10 different salt solutions. Skin hardness was measured via a puncture test, and two groups of berries with different skin hardness were selected for each ripening stage: soft (<0.40 N) and hard (>0.50 N). Anthocyanin skin extraction was evaluated in a hydroalcoholic model solution and the kinetics of skin dissolution was monitored. For each ripening stage, the harder skin had greater anthocyanin extractability. Significant interactions between ripening stage and skin hardness were found in the composition of individual anthocyanins present in the extract.