Reduction of bitter component of pomelo juice by chemical treatment and immobilized enzyme

Abstract

Effect of pH, total soluble solids (TSS), β-cyclodextrin, immobilized enzyme on removal of naringin and on quality of pomelo juice was studied. The maximum reduction in naringin content (0.34 mg/mL) was observed in juice, treated with immobilized naringinase compared to control (1.1mg/mL). Change of pH from 3.5 to 4.5 reduced naringin content from 31.8% (pH 3.5) to 40.9% (pH 4.5). However, lowering of bitter principle was 49% for 30°B and 43.6% for juice of pH 4.5 & TSS 30°B. Minimum changes in physicochemical parameters were observed with immobilized enzyme treated juice. Effect of these treatments on the activity of enzymes were also studied. Minimum amylase activity was observed with immobilized enzyme treated sample 18.9 U to that of control 32 U. Change in pectin methyl esterase (PME) activity was not so significant with an increase of pH. Maximum reduction of PME activity was observed with sample of 30°B TSS. However, retention of peroxidase activity was maximum for β-cyclodextrin treated sample 2.1 K₁×10³/mL compared to control 2.7 K₁×10³/mL. Treatment with immobilized enzyme gave an acceptable debittered pomelo juice.