Isolation and characterization of naringinase enzyme and its application in debittering of Pomelo juice ( Citrus grandis ): A comparative study with macroporous resin

Abstract

The naringinase enzyme was isolated from Citrus macroptera peel and pomace using Aspergillus niger for immobilization and debittering of juice. A comparative study of the effect of debittering using immobilized enzyme and resin on the physicochemical and phytochemical properties of the juice were carried out. The optimum hydrolytic conditions and Michaelis constant for an immobilized enzyme were observed at pH 4, 70℃, and 16.75 μg/ml, respectively. Adsorption of naringin onto resin followed pseudo‐first‐order with a regression coefficient of 0.92. Naringin content was reduced up to 73.28% in 4 min by resin and 79.76% in 120 min by the enzyme. We reutilized resin and immobilized enzyme effectively to debitter the juice up to seven cycles. Treatment for less than 2 min and 90–120 min using resin and enzyme, respectively, could retain the sizable amount of bioactive components in juice and immobilization retained 62% enzymatic activity during 2 months of storage at 4°C. PRACTICAL APPLICATIONS: Pomelo being a rich source of bioactive nutrients faces slow commercialization due to immediate bitterness (naringin), thus in the present study, Citrus macroptera waste including peel and pomace was efficiently utilized to produce naringinase enzyme for the debittering of pomelo juice. Also, adsorption kinetics of naringin using macroporous resin is presented, which will further help in the selection of optimum time and dose for the removal of naringin from the juice. More importantly, their effect on juice composition helped in the selection of the potential candidate for the industrial purpose with negligible or minimum loss of nutrients.