Anthocyanin during winemaking

A.2 Chemical Reactions of Anthocyanins During Winemaking Main Anthocyanin-... 

Fig. 9A.3 Main chemical reactions of anthocyanins during winemaking...

The fermentation usually is complete within 30 or 40 days. During this period additional anthocyanins are extracted from pomace and the color stabilizes due to polymerization between the anthocyanins and tannins. Winemakers call this process pomace "maturation". Moreover, due to the increasing alcohol concentration, many other metabolites are extracted from the pomace. In addition, yeast metabolites contribute to the aromatic complexity of the wine. 

However, the dissolvent effect of SO2 is manifest in rose winemaking, since the phenolic compound concentration is low in this case. In fact, SO2 can be detrimental to white winemaking. This dissolvent effect may also affect red grapes if they are insufficiently ripe, and pigment extractability is poor. In that case, snlfiting facilitates anthocyanin extraction in the early stages, especially during cool-temperature maceration (Section 12.5.2). 

Table 12.17. Evolution of anthocyanin and color intensity in a heated and pressed must, compared with traditional winemaking, during alcoholic fermentation (Rib6reau-Gayon et al., 1976)...

Contact time, temperature and sulfiting are factors that influence phenolic compound dissolution and color in rose wines (Castino, 1988). Sulfur dioxide is known to have a certain dissolvent power (Section 8.7.5). It is not manifested during traditional red winemaking, due to the preponderant effects of other factors (duration, temperature and pumping-over). Yet when maceration is limited, the effect of sulfiting is obvious. Table 14.3 shows the impact of the winemaking techniqne on the color intensity and phenolic componnd concentrations of rose wines. Sulfiting promotes anthocyanin dissolution and color enhancement. It is not easy to control the conditions that will produce the required color and phenolic structure, as they depend on the specific characteristics of the wine. 

---