Studies on immobilization of polyphenoloxidase from tea leaves & mango peel.
Polyphenoloxidases (EC 1.14.18-1) were isolated from mango peel and green tea leaves and immobilised by using various supports such as polyacrylamide gel, DEAE-Sephadex, DEAE-cellulose, collagen, arylamine glass and alkylamine glass. Various properties of the immobilised enzymes like optimum temp. and pH, Km values, substrate specificity, thermal stability, storage stability and reusability were studied and compared with those of the native enzyme. Results showed that polyphenoloxidase preparations from mango peel and tea leaves exhibit different properties even in the native stage and that their behaviour and response after immobilisation are also different. The higher specific activities, lower Km values, high reusability, good storage stability, wider pH and temp. optima of the immobilised enzyme might have advantages over the soluble during processing operations such as fermentation and manufacture of instant tea. It was concluded that tea leaf polyphenoloxidase entrapped in polyacrylamide gel and complexed with collagen, and mango peel polyphenoloxidase immobilised in DEAE-Sephadex are quite satisfactory.