The functions of sulfur dioxide are sterilization and antioxidant, preventing the grape juice from being contaminated by bacteria and affecting the fermentation effect. Therefore, it is generally necessary to add sulfur dioxide while crushing.

The function of pectinase is to increase the juice yield of grapes and facilitate more complete fermentation.

The reason why pectinase is added 2 hours after adding sulfur dioxide is to prevent the sulfur dioxide aqueous solution (i.e. sulfurous acid) from affecting the activity of pectinase. Hope it will be adopted.