Determination of malvidin-3,5-diglucoside content in wines from Cabernet Cortis and three Italian-resistant hybrids, with preliminary evaluation of oenological glycosidases for enzyme-induced breakdown of malvidin-3,5-diglucoside and malvidin-3-glucoside

The content of malvin (malvidin-3,5-diglucoside) was determined in a set of wines obtained from Cabernet Cortis and other three recently introduced grape-resistant hybrids (Cabernet Volos, Merlot Khantus and Merlot Khorus) produced in South Tyrol (Italy), to establish their conformity to legal requirements and suggest winemaking approaches for their production and use. Different skin maceration times and ageing periods were considered for the wines investigated. Malvin content exceeded the limit of 15 mg/L, imposed by the Italian government for the commercialization of wines, in 18 out of 21 samples and showed a significant decrease during wine ageing (by about 40–50% every 12-month period) with the scarce effect of maceration time and fermentation temperature. Single-cultivar wines became suitable for commercialization after ca. 7 years ageing, following traditional winemaking approaches. The use of two commercial enzymatic pectolytic preparations indicated for aroma enhancement and possessing β-glucosidase activity was also investigated at two different dosages, to increase the degradation rate of malvin in wines after winemaking. They are unsuitable for significant malvin content decrease within a 6-month time lapse.