1, hygiene problems: the fermentation container is not cleaned, and the container is not cleaned when stirring, which may lead to bacterial infection.

2. Grape raw materials: In order to increase the yield of grapes, many growers are likely to use pesticides in the process of grape growth. However, in the process of homemade wine, we do not advocate washing the grapes clean, because it depends on the microorganisms on the grape surface to guide the fermentation.

3. Selection of containers: Many containers are used in the whole process of brewing, and the most important one is the fermentation container. There is no doubt that if we use glass and ceramics as fermentation containers, it is safe and reliable. And if you use stainless steel or even iron containers as fermentation containers, it is likely to brew poison.

4. Temperature problem: long-term irradiation causes grape mutation; Too high a temperature can also cause enzyme mutation, and other factors will make homemade wine toxic.