Apple juice clarification by a purified polygalacturonase from Calonectria pteridis

Polygalacturonases are extensively used in food industries for pectic substances degradation. They are essential for fruit juice clarification due the degradation of insoluble viscous pectinacious compounds. Polygalacturonase production by the fungus Calonectria pteridis was performed on submerged fermentation and, after purification, the enzyme showed a molecular weight of 68 kDa. The highest polygalacturonase activity occurred at pH 4.0, and the enzyme preserved more than 70 % of its activity at pH values between 3.6 and 6.0. The optimum temperature was 60 degrees C. The half-life values at 50 and 60 degrees C were 260 and 66 min, respectively. The KM value was 0.52 mg/mL for the substrate polygalacturonic acid and the presence of He and SDS completely inhibited the enzyme activity. The purified polygalacturonase was applied for apple juice clarification and it resulted in a volume and an amount of reducing sugars released increase of 10.65 and 40.93 %, respectively. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.