Abstract: The qualities of different maturity plums, the effects of pectinase process on juice rate, acclimation of the high acid tolerant acetic acid bacterium and clarification of plum fruit vinegar were studied in this paper. The results showed that the optimum maturity degree of raw juice plum vinegar production is 8 maturity; 200 mg/L pectinase treatment could increase the juice rate by 12.0%, and it is favorable for juice extracting. Acetic acid fermentation was carried out under lower acid by using CaCO3 to decrease the acid of plum wine. The acetic acid bacterium was inoculated into higher acid wine gradually. The acetic acid bacterium adapted to the high acid environment gradually and could ferment high acid plum wine finally. The transmittanty of plum vinegar could reach above 92% by adding 1.4 g/L bentonite after 100 mg/L pectinase treatment for 3 hours.

Key words: plum, raw juice vinegar, acetic acid fermentation, brewing techniques