There are many varieties of wine grapes, but they are very different from the grapes we usually eat. Wine grapes have thick skin, less meat, more juice and small particles, which are difficult to eat. This kind of grape has high sugar content, large seeds and many tannins. If you chew a wine grape, you will feel fruity and slightly bitter, accompanied by the "squeaking" sound of pulp separation.

Compared with edible grapes, wine grapes have higher sugar and acidity, so the alcohol concentration of wine brewed with them will exceed 12%, and the pH value will be lower than 3.6, which can protect wine from the harm of bacteria. The sugar content of edible grapes is low, the alcohol content is only 8% to 9%, and the acidity is not high enough. Therefore, if you must use edible grapes to make wine, you must add extra acid and sugar. The reason is that sugar will produce carbon dioxide and alcohol after fermentation. Alcohol is the most powerful preservative, but wine must reach a certain alcohol concentration to prevent corruption and deterioration. In addition, if the acidity of wine is too low, it is easier to breed bacteria after contact with air, and gradually turn wine into vinegar.