Extraction of Proanthocyanidins during Fermentation of Muscat Bailey A and Cabernet Sauvignon Wines

As we reported earlier, Muscat Bailey A (MBA) wine has very low proanthocyanidin (PA) content compared with Cabernet Sauvignon (CS) and Merlot wines. Whereas PA concentration in CS was maintained at the maximum level during maceration, that in MBA reached a maximum approximately four days after maceration and drastically decreased thereafter. In this study, the model wine extraction profiles of seed total phenols (TPs) and PAs in MBA and CS were compared. The final TP concentration extracted from seeds obtained from 1 kg of grape berry with 1 L of model wine was 256 mg/L and 1,428 mg/L for MBA and CS, respectively. The final PA concentration was 29 mg/L for MBA and 738 mg/L for CS. Changes in TP and PA concentration in fermenting must were also compared. Wines were made with/without skins and seeds. For wines fermented without seeds (skin samples), TP concentration peaked at days 4 to 6 and declined thereafter for both cultivars. For wines fermented without skin (seed samples), TP concentration started to increase from day 7 to reach the maximum concentration of 1,191 mg/L for CS, but not for MBA. The same tendency was shown for PA concentration. These findings suggest that the extractable PA content in grape berry differs between the two cultivars. The final TP concentration was 2,107 mg/L for CS wine and 1,013 mg/L for MBA wine, and the difference was only twofold. In contrast, the final PA concentration was 485 mg/L for CS wine and 19 mg/L for MBA wine, and the difference was 25-fold. Abbreviations: CS, Cabernet Sauvignon; MBA, Muscat Bailey A; PA, proanthocyanidin; TP, total phenol.