Naringinase (EC3. 2. 1. 40) contains α-L-rhamnosidase and β-D-glucosidase activities. The gene of a-L-rhamnosidase has been cloned and expressed with marked activity in Escherichia coli. The recombinant naringinase provides an economical and easily available source of this enzyme in food and pharmaceutical industries. Naringin, the principal bitter flavonone glycoside and the primary bitter component in grape fruit juice, can be hydrolysed by naringinase into tasteless naringenin. The main goal of this work was the optimization of the enzymatic activity of immobilized naringinase for removal of the bitter taste and the maintenance of the juice characteristics and properties. In this study, naringinase was immobilized in alginate sodium to improve its activity recovery. The results show that adopting 3% sodium alginate as carrier and using the method of crosslinking-embedding-crosslinking through 2. 0% glutaraldehyde were optimized. The activity recoveries of naringinase could reach 129. 64% under optimal conditions. Moreover, the activity recoveries of naringinase increase with decreasing concentration of naringinase solution. This is a promising result of reducing production cost for future application of immobilized naringinase in the citrus juice industry. On six consecutive repeated use of immobilized naringinase, 90% retained activity were observed. Michaelis constant (Km) and maximum reaction velocity (Vm)were calculated for free and immobilized enzyme systems. Effects of temperature and pH on enzyme activity were estimated. [
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