1, gas is generated in the fermentation process, and the mouth of the container should not be sealed, just cover it slightly;
2, the whole process can't contact with iron and copper tools, which will bring iron and copper damage;
3. You can't make wine with rotten grapes, otherwise the wine will be sour and taste bad;
4. Grapes need to be squeezed and put into containers, which is beneficial to the dissolution of beneficial substances;
5. Don't wash too many grapes. The power of fermentation comes from wild yeast on the skin.
6, can't contact with raw water in the process of fermentation, in case of infection with mixed bacteria, leading to fermentation failure;
7. Avoid direct sunlight during the whole process, and the temperature is within 35 degrees.
As long as we pay attention to hygiene, do not infect miscellaneous bacteria, control fermentation temperature, avoid iron and copper tools and direct sunlight, the fermented wine will not contain any harmful substances and can be safely drunk.