The role of oxygen in white wine maturation
If oxygen plays an important role in the maturation of red wine, in the maturation of white wine, oxygen has no effect on quality improvement. On the contrary, during the entire brewing process, including mechanical processing, fermentation, storage, etc. of raw materials, oxygen is the enemy of white wine. However, under the premise of reasonable use, the excessive oxidation of grape juice can improve the sensory quality of white wine.
The higher the damage rate and mildew rate of grape raw materials, the higher the content of oxidase in grape juice and the greater the harmful effect of oxygen. After the fermentation is over, the new white wine easily loses its refreshing and fruity flavor due to oxidation, and the color becomes darker. therefore. During white wine production, oxidation should be prevented as much as possible. H 2 S 味，或促使酵母菌将剩余的残糖转化为酒精，使发酵彻底，或促进释放葡萄酒中的 CO 2 时，才对白葡萄酒进行通气处理。 Ventilation of white wine is only possible when the wine may have an H 2 S flavor, or when yeast is required to convert the residual sugars into alcohol, to complete fermentation, or to promote the release of CO 2 in the wine.
If white wine is stored in oak barrels, on the one hand, the wine is slowly oxidized; on the other hand, tannins and other substances contained in the oak enter the wine. These two effects cause the following changes in white wine:
果香味逐渐减弱、消失，陈酿味，特别是哈喇榛子味逐渐出现并加重。 (1) The fruit aroma gradually weakens and disappears, and the aging flavor, especially the hazelnut flavor, gradually appears and increases. If the hazelnut taste is light, it is a pleasant fragrance; if it is too strong, most people don't like it. In addition, white wines are generally required to be refreshing and fruity, while only a few people require aging. therefore. Only a few brand-name wines with special styles require aging, but the characteristics brought about by barrels and oxidation are too obvious.
颜色逐渐加深，呈黄色、金黄色甚至带褐色。 (2) The color gradually deepens, showing yellow, golden yellow and even brown. This is because the flavones are oxidized to yellow salts under aerobic conditions, and then brown pigments are formed.
Except for a few special white wines, oxidation should be strictly prevented before bottling.
CO 2 的释放。 It should be pointed out that if the storage conditions of white wine are too closed, it will prevent the release of CO 2 formed by fermentation . CO 2 含量。 As with red wines, the CO 2 content of white wines should be determined before each bottling and, if necessary, adjusted for white wines . CO 2 的最佳含量约为 0.5~0.7g/L 。 The optimal content of CO 2 in dry white wine is about 0.5 ~ 0.7g / L.