Wine Research Centre, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada.
Department of Horticulture, Plant and Soil Sciences Building, Michigan State University, East Lansing, MI, 48824, USA.
Sci Rep. 2022 Mar 9;12(1):3838. doi: 10.1038/s41598-022-07925-7.
In cool-climate viticulture, the short growing season can influence grape seed maturation by reducing the apparent oxidation of flavan-3-ol monomers and associated increase in seed browning. A reduction in seed maturation increases the potential extraction of flavan-3-ol monomers into wine during maceration operations, heightening bitterness. Here, we carried out a 2 × 2 factorial experiment to test the ability of freezing and heating treatments to advance maturation (decrease flavan-3-ol, improve browning) of (Vitis vinifera L.) Pinot noir and Cabernet Sauvignon seeds over a 24-h incubation period. Only freezing significantly increased seed browning in both cultivars. Subsequent correlations with seed flavan-3-ol monomer concentrations suggest that freezing enhanced the oxidation of these compounds. Interestingly, natural ripening and freezing reduced galloylated flavan-3-ol monomers to a greater extent than non-galloylated ones. This study provides new information regarding the susceptibility of flavan-3-ol monomers to freezing and heating, and also suggests that freezing can advance the maturation the seeds of under-ripe red vinifera grapes.
在凉爽气候的葡萄种植中，较短的生长季节可能会通过减少黄烷-3-醇单体的表观氧化和种子褐变的相应增加来影响葡萄种子的成熟。种子成熟度的降低增加了在浸渍过程中将黄烷-3-醇单体提取到葡萄酒中的潜力，从而提高了苦味。在这里，我们进行了一项 2×2 析因实验，以测试冷冻和加热处理在 24 小时孵育期内对（Vitis vinifera L.）黑比诺和赤霞珠种子成熟（减少黄烷-3-醇，改善褐变）的影响。只有冷冻处理在两个品种中均显著增加了种子的褐变。随后与种子黄烷-3-醇单体浓度的相关性表明，冷冻增强了这些化合物的氧化。有趣的是，与非没食子酰基化的单体相比，自然成熟和冷冻处理更能降低没食子酰基化的黄烷-3-醇单体。这项研究提供了关于黄烷-3-醇单体对冷冻和加热的敏感性的新信息，并且还表明冷冻可以加速未成熟红葡萄种子的成熟。
