Production of new immobilized β-glucosidase preparation for food industrial purposes by using kinetic desorption method

A new β-glucosidase enzyme preparation for food industrial use was produced. The enzyme was immobilized on an anion exchange resin Amberlite IRA-900 by adsorption followed by cross-linking of the enzyme molecules on the surface of the carrier with glutaraldehyde. To examine and develop the parameters of the steps of the immobilization process, a test method called kinetic desorption method was worked out that permitted the examination of interactions between the enzyme and the carrier. By using the efficiency of kinetic desorption method developed in our laboratory we determined the optimal conditions of procedure: the concentration (0.10 M) of the buffer (sodium acetate pH 5.50), the ratio of the carrier and the enzyme (10:1), the 24 h reaction time at 25 °C for the adsorption step, the pH of the buffer (pH 5.50), the time of treatment (30 min), and the concentration [0.25% (m/v)] of glutaraldehyde for the cross-linking process. The maximum yield of immobilized enzyme activity was 21.4%, the immobilization process changed the pH optimum of catalytic activity from 5.50 to 4.50 and the temperature optimum from 50 °C to 60 °C. The immobilized enzyme is to be tested in various food industrial processes

Studies of biochemical parameters characteristic of oxidative damage in different apple cultivars ( Malus domestica Borkh.) during storage

Biochemical parameters, characteristic of oxidative damage (POX and PPO activity, FRAP value and TP content) were used to study the prolonged storage of novel apple cultivars resistant to several apple tree diseases (Re-apples). In period I, results of apples stored from September to November and from September to December were compared. In period II, results of apples stored from September to December and from September to April were compared. In period I, significant increase in the activity of peroxidase and polyphenoloxidase enzymes, slight increase in total phenol content and slight decrease in FRAP values were detected. In period II, the parameter values decreased. No direct correlations were found between the measured biochemical parameters and the keeping of quality during the prolonged storage, therefore additional comparative studies are needed