In this regard, Zhu Yi, associate professor of the College of Food Science and Nutritional Engineering at China Agricultural University, explained that wine is made from fresh grapes and fermented by microorganisms. In the brewing process, precipitation may occur for the following reasons: The wine contains tartaric acid, the organic acid will crystallize when the temperature is lowered, and the tartaric acid in the storage process is combined with the tannin and wine pigments in the wine. Flocculation occurs; iron ions in wine undergo oxidation reactions when oxidases are deactivated to produce precipitated substances.
Zhu Yi pointed out that a small amount of sediment in wine generally does not affect normal drinking. On the contrary, this is precisely a sign of wine's maturity, because the unstable substances that affect the taste of wine have been separated from the wine, so that the wine becomes more pure and wine. The taste structure is more stable and the taste is more mellow and lubricious. In China's new wine standards, there is a clear clarification on the clarity of wines. Wines that have been bottled for more than one year are allowed to have a small amount of sediment. So, don't worry about finding precipitate in wine.
In order not to affect the consumer's experience, many wine bottles have a bulge at the bottom and a small, deep groove at the edge. This is to make the sediment fall in the ditch and not easily disperse. When drinking, you should gently pour the wine so that the sediment at the bottom of the bottle floats due to the shaking and affects the appearance of the wine.
Zhu Yi reminded that the following points should be noted when storing wine: First, bottled wine should be stored in a stable, dry, dark, cool place, which can prevent the inactivation of oxidase in wine and avoid the iron ion precipitation. In addition, it can also avoid the reduction of resveratrol in human body that has the effects of reducing blood fat, antithrombosis and preventing coronary heart disease in wine; secondly, if the bottle mouth is opened, then cork stopper is used to seal and keep the cork moist and prevent it. Contamination in the air caused by the turbidity or deterioration of wine; Third, for the bottled wine has been completely sealed, try to isolate the air or put a small amount of vitamin C tablets in the wine, to prevent the oxygen in the air and wine Compounds react to produce floc, while avoiding the reaction of oxygen and phenolic substances to turn the wine brown. Fourth, a small amount of lemon juice can be added to the wine to lower its pH, thereby further avoiding precipitation of tartaric acid crystals. At the same time, citric acid can form soluble complexes with iron ions, which can protect iron from precipitation by oxidation. (Text / Cao Yu)