Related knowledge:

1. Acetobacter is a harmful bacterium floating in the air. When wine is polluted by acetic acid bacteria, a white film will be formed on the surface of wine. With the passage of time, more and more white films will be formed by acetic acid bacteria, which will seriously affect the quality of homemade wine.

2. The reason why self-made wine is polluted by air produces white film is that the wine is in contact with the air during brewing, which is often said that the wine is polluted by air. White foam at least fermented carbon dioxide and other products, not bad. Also, when brewing, the grapes were washed too clean, and all the white hairs on the skin were washed away. It's nothing to add something. When the alcohol concentration rises, it will naturally kill other bacteria.