Impact of maceration enzymes on skin softening and relationship with anthocyanin extraction in winegrapes with different anthocyanin profiles.

The impact of an enzyme preparation on the extraction of grape skin anthocyanins into a wine-like solution was evaluated during maceration (25 °C, 8 days). The study was performed on Vitis vinifera L. cv. Cabernet Sauvignon and Nebbiolo because of their different anthocyanin profiles, which are mainly composed of tri- and di-substituted forms, respectively. Maceration enzymes enhanced the skin releasing capacity for anthocyanins between 8% and 15% more depending on the enzyme dose and variety, and shortened the time required to reach the maximum extraction yield by about 40 h, when compared to the control samples. The effect of enzymes on the profile and total content of anthocyanins during maceration was significant only for Cabernet Sauvignon. Therefore, a variety effect was found. Particularly, the relative amount of malvidin glucosides increased up to 9% more whereas that of delphinidin, cyanidin and peonidin glucosides decreased up to 5, 2 and 3% more, respectively, with the addition of the enzyme preparation. The results also showed lower anthocyanin degradation at maceration times longer than 72 h with the use of enzymes. Furthermore, the relationship between this enzyme effect and the instrumental skin hardness was assessed for the first time, as no previous study deals with the variation in the mechanical properties of the berry skin after using maceration enzymes. Significant positive relationships were found between the skin softening and the anthocyanin extraction yield (R>0.69, p<0.01), which confirmed that the skin degradation by enzymes facilitates the anthocyanin release.