Tannase Immobilization by Chitin-Alginate Based Adsorption-Entrapment Technique and Its Exploitation in Fruit Juice Clarification

Abstract

Present study aimed to immobilize the bacterial tannase on suitable carrier and its subsequent applicability in fruit juice clarification. Tannase from Bacillus subtilis PAB2 was immobilized on chitin-alginate bead by adsorption-entrapment technique. Maximum immobilization (82 %) with an activity yield of 67 % was achieved in presence of 1.5 % (w/v) sodium alginate, 1 M CaCl2 and 1 % (w/v) flake chitin, incubation at 4 °C temperature, and adsorption period of 90 min. Thermal and pH stabilities of immobilized tannase increased in respect to free tannase. The storage stability and reusability of the immobilized tannase were also improved significantly, retaining 83 % activity after storing 90 days at 4 °C and it showed 79 % residual activity after 10 times repeated use. Then, immobilized tannase was applied for clarification of jamun and cashew apple juice to investigate its debittering property. Enzymatic treatment removed 60 and 51 % tannin from jamun and cashew apple juice, respectively, after incubation at 40 °C for 120 min. Other qualitative indicator viz., total titratable acidity, color, and viscosity also reduced, whereas, flavonoid (460.49 μg/ml; 994.44 μg/ml), glucose (6.95 mg/ml; 9.19 mg/ml), and antioxidant activity (69.28 %; 78.44 %) were significantly increased in clarified jamun and cashew apple juice, respectively.