Abstract:

The effects of separate and combined use of pectinase and fruit pulp-hydrolyzing enzyme, a commercial composite
enzyme preparation, total enzyme concentration, hydrolysis time and temperature on fruit yield and total antioxidant capacity
(T-AOC) of blueberry juice were studied by using one-factor-at-a-time and orthogonal array design methods. The optimal
conditions for enzymatic hydrolysis of blueberry pulp were found as follows: ratio of pectinase to fruit pulp-hydrolyzing enzyme of
1:1, total enzyme concentration of 6 g/L, 45 ℃ and 3.5 h. The yield of juice obtained under these conditions was (72.51 ± 1.51)%,
which is (77.18 ± 1.64)% higher than that observed without the enzymatic treatment, and the T-AOC of the resulting juice was
(224.07 ± 3.26) U/mL, which is (96.45 ± 2.51)% higher than that of native blueberry juice without the enzymatic treatment. In
addition, the juice obtained from the enzymatic treatment contained (753.92 ± 10.41) mg/L anthocyanins and (2649.77 ± 70.40)
mg/L total phenols, showing an increase by (2.40 ± 0.15)-fold and (75.66 ± 5.31)% over the native counterpart, respectively.
Therefore, a high antioxidant capacity of blueberry juice was achieved.

Key words: blueberry, enzymatic hydrolysis, total antioxidant capacity (T-AOC), anthocyanins, total phenols