Abstract:In this paper, Fuji apple was used as raw material and the changes of β-glucosidase, pectinase, protease and amylase activities in pure and mixed cultures (MST1: 105 cfu/mL Saccharomyces cerevisiae/106 cfu/mL Torulaspora delbrueckii; MST2: 104 cfu/mL Saccharomyces cerevisiae/106 cfu/mL Torulaspora delbrueckii) during apple juice fermentation were studied. The results showed that in pure culture, except for α-amylase and pectinase, the maximum enzyme activities of β-glucosidase and acid protease produced by S. cerevisiae 32168 were higher than those of T. delbrueckii 1004, the maximum activity level were 2.03 nmol/(min·mL) and 43.93 nmol/(min·mL), respectively; the areas under the enzyme curve were 10.65 and 223.73, respectively. The area under the pectinase curve was higher in T. delbrueckii 1004, reaching 14.17, while there was no significant difference in α-amylase. In the mixed culture, except for acid protease and α-amylase, the maximum enzyme activity values of β-glucosidase and pectinase were higher than those of the pure culture and the maximum enzyme activity value was up to 2.37 nmol/(min·mL) and 4.56mg/h·mL, respectively; the areas under the enzyme curve were up to 15.11 and 19.71, respectively. A lot of enzymes were produced by pure and mixed of T. delbrueckii and S. cerevisiae throughout the fermentation process. These enzymes help to catalyze the hydrolysis of natural precursor polymers in apple juice and improve the quality of cider. The mixed inoculation can be used as another different fermentation method from the pure fermentation of Saccharomyces cerevisiae.
