The use of commercial pectinase in fruit juice industry. Part 3. Immobilized pectinase for mash treatment

Enzymatic mash treatment is a well-known modern process for gaining more juice from fruits and vegetables. According to the technique, cell wall and middle-lamina pectin of the fruit are degraded by pectinase activities. Besides increasing press capacity and the yield of juice up to 20%, it has also a positive effect to achieve high carotene and dry matter content of the product. The aim of the research was to investigate the activity and reusability of immobilized commercial pectinase named as Pectinex Ultra SP-L on carrot puree. Immobilization process was carried out by using ion exchange resin particles washed with 0.05 M phosphate buffer at pH 4.5. Pectinase activity of immobilized enzyme was determined by the measurement of viscosity reduction of pectin solution model system at pH 4.5 and 35 degreesC and found to be 1.252-pectin (w/v, %)/s mi. Activity loss was only 20% after nine batches run model system studies. The optimum initial enzyme concentration was detected by measuring the highest pectinase activity in pectin solution and found to be 6% (v/v). Enzyme immobilized particles were added to the carrot puree with an amount of 1.5 g particle/100 g puree at pH 4.5 and 35 degreesC to degrade soluble and insoluble pectin and haze-provoking polysaccharides. The activity of immobilized enzyme was determined by measuring pH, dry matter content and viscosity of the puree. Immobilized enzyme preparation reduced the viscosity of the carrot puree from 90 to 6.5 Poise, after 60 min of incubation. While the viscosity and pH of the puree were decreased, dry matter content and total yield were found to be increased because of the polysaccharide degradation. An average yield increment was 30.23% with respect to the yield obtained from non-enzymic processed carrot juice. Immobilized enzyme was used 5 times in carrot puree medium at the above described conditions and the activity loss was found to be only 6.5%. Activity of the immobilized enzyme was quite stable. (C) 2000 Elsevier Science Ltd. All rights reserved.