Abstract: Pectinase and pectinex were used separately to produce kiwifruit juice from kiwi fruit pulp in the current study. To find a better enzymatic pretreatment for the production of kiwifruit juice, one-factor-at-a-time and orthogonal array design methods were used to optimize hydrolysis conditions based on juicr yield, VC preservation rate, changes of juice color and aroma. The results showed that both enzymes could improve the yield of kiwi fruit juice substantially. However, pectinase required more intense hydrolysis conditions and had greater effect on vitamin C content and juice color and aroma compared to pectinex. Mild conditions were required for pectinex treatment, which resulted in better overall quality index of kiwifruit juice. The optimal conditions for pectinex hydrolysis were 2 h of hydrolysis at an enzyme dose of 10000 U/kg and 30 ℃. Under these conditions, the juice yield and vitamin C preservation rate were 0.853 mL/g and 67%, respectively. This study demonstrated that pectinex is more suitable for the production of kiwifruit juice.

Key words: kiwifruit, juice yield, enzymolysis, pectinex, pectinase