Relations between break skin force and anthocyanin extractability at different stages of ripening

This work evaluated the extractability of anthocyanins from winegrapes with different skin hardness at two different stages of ripening. Skin hardness was assessed by Texture Analysis, an interesting analytical technique because of its rapidity and low cost. Grape berries of cv. Brachetto were calibrated according to their density estimated by flotation in ten different salt solutions and two classes of maturity were studied. For skin hardness measurement a puncture test was performed and for each class, two groups of berries with different skin hardness were selected: the soft ones (<0.40N) and the hard ones(>0.50N). Anthocyanin skin extraction was evaluated in hydroalcoholic model solution and kinetics of their dissolution was monitored. For each level of maturity the more hard skin showed a higher degree of anthocyanin extractability. Significant interactions between stage of ripening and skin hardness was found in the composition of individual anthocyanins present in the extract.