Generally, the fermentation stage begins 24~48 hours after canning. After fermentation, a large number of bubbles will float, and grape pomace will also float, forming hard pomace.
Because the fermentation process also needs a little oxygen and produces a lot of carbon dioxide gas, so don't seal it and leave a vent hole to avoid falling into dust and insects.
Cap pressing: The thick and hard cap formed by floating skin dregs is pressed into wine, which can prevent skin dregs from rising and breeding bacteria, and can strengthen skin infiltration, generally 2-4 times a day.
Extended data
1, temperature: during the main fermentation, the barrel temperature is controlled between 15-30 degrees, and the barrel temperature is subject to the bottom temperature of the slag cover; When the temperature is low and the fermentation time is prolonged, the color of the wine is lighter, but the taste and quality are better. High temperature shortens the time, and the wine color is better, but the taste and quality are not as good as that of low temperature fermentation.
2. Fermentation time: The main fermentation usually lasts 7- 10 days, and the specific time depends on grape varieties, sugar content and fermentation temperature. To determine the separation time.
The standard of separation and filtration is: after a period of intense fermentation (producing a lot of bubbles), the amount of bubbles is greatly reduced or disappeared, and when the strong wine smell and sweetness disappear, it can be filtered.
It is best not to filter for a long time, because too long will increase tannins and other substances that affect the taste of grape skins and increase the astringency of wine.
Baidu Encyclopedia-Homemade Wine