Effect of Cap Management Frequency on the Phenolic, Chromatic, and Sensory Composition of Cabernet Sauvignon Wines from the Central Coast of California over Two Vintages.

Cabernet Sauvignon from the California Paso Robles AVA was processed with a contrasting array of cap management frequencies, consisting of punch-down (PD) frequencies (0, 1, 2, and 3 PD/day) over two vintages, one of which the fruit was harvested at two contrasting maturity levels. Wines followed with up to 3 years of bottle aging for basic and phenolic chemistry, and the wines of the second harvest of 2020 were submitted to sensory analysis. There were almost non-existent effects due to the frequency of punch downs on parameters such as ethanol, pH, titratable acidity, lactic acid, and glucose + fructose. In 2019, the chromatic differences between different PD regimes were subtle, and minor effects of the punch-down frequency were observed for tannins and total phenolics. During the early stages of alcoholic fermentation, higher levels of all anthocyanin classes were observed in 1 PD wines and the lowest levels in 0 PD wines. The anthocyanin content of the wines of the first harvest (unripe) was 27% higher than that of the wines of the second harvest (ripe), but these differences disappeared after 3 years of bottle aging irrespective of the vintage and harvest date. Acylated anthocyanins were preferentially lost during aging, especially in 2019 wines and, to a lesser extent, in 2020 wines. In 2020, the polymeric pigment content of the wines of the second harvest was higher than in the wines of the first harvest, with 3 PD wines showing higher polymeric pigments and yellow hues than 0 and 2 PD wines after 3 years of bottle aging. Sensory analysis of the second harvest of the 2020 wines showed that the wines of all four PD regimes were perceived as drying, signifying they were perceived as equally astringent, which is consistent with comparable tannin levels on said wines. The perception of bitterness increased with the frequency of punch downs; thus, 3 PD wines showed the highest bitterness perception. It was concluded that in sufficiently warm fermentations and small volumes, phenolic extraction occurs regardless of fruit maturity and under conditions of minimum mixing.