| Popis: |
In cool-climate viticulture, the short growing season can influence grape seed maturation by reducing the apparent oxidation of flavan-3-ols and associated increase in seed browning. A reduction in seed maturation increases the potential extraction of flavan-3-ols into wine during maceration operations, heightening bitterness. Here, we carried out a 2x2 factorial experiment to test the ability of freezing and heating treatments to artificially “ripen” seeds (decrease flavan-3-ols, improve browning) of (Vitis vinifera L.) Pinot noir and Cabernet Sauvignon over a 24-hour incubation period. Only freezing significantly increased seed browning in both cultivars. Subsequent correlations with seed flavan-3-ols concentrations suggest that freezing enhanced the oxidation of these compounds. Interestingly, natural ripening and freezing reduced galloylated flavan-3-ols to a greater extent than non-galloylated ones. This study provides new information regarding the susceptibility of flavan-3-ols to freezing and heating, and also suggests that freezing can artificially ripen the seeds of under-ripe red vinifera grapes. |
