Immobilization of β-glucosidase and its aroma-increasing effect on tea beverage

beta-Glucosidase was effectively immobilized on alginate by the method of crosslinking-entrapment-crosslinking. After optimization of the immobilized conditions, the activity recovery of immobilized beta-glucosidase achieved to 46.0%. The properties of immobilized beta-glucosidase were investigated. Its optimum temperature was determined to be 45 degrees C, decreasing 10 degrees C compared with that of free enzyme, whereas the optimum pH did not change. The thermal and pH stabilities of immobilized beta-glucosidase increased to some degree. The K-m value for immobilized beta-glucosidase was estimated to be 1.97 x 10(-3) mol/L. The immobilized beta-glucosidase was also applied to treat the tea beverage to investigate its aroma-increasing effect. The results showed that after treated with immobilized beta-glucosidase, the total amount of essential oil in green tea, oolong tea and black tea increased by 20.69%, 10.30% and 6.79%, respectively. The storage stability and reusability of the immobilized beta-glucosidase were improved significantly, with 73.3% activity retention after stored for 42 days and 93.6% residual activity after repeatedly used for 50 times. (C) 2009 Published by Elsevier B. V on behalf of The Institution of Chemical Engineers.