Characteristics of pectinesterase isolated from bramley apple waste

Pectinesterase was isolated from Bramley apple waste (peel, cores and offcuts) and its characteristics were determined. Optimum pectinesterase activity was obtained between pH 7.0 and 9.5 and activity was still detectable at 5.0. The enzyme was stable over a wide pH range in the presence of substrate, with over 90% of the activity retained after 5 min at pH 2.5. Pectinesterase activity increased with temperature up to 60°. Activation energy was calculated at 32 kJ mol−1 K−1 between 20 and 50°. Optimum activity was obtained in sodium chloride concentrations between 0.025 and 0.20 M with activity declining at higher salt concentrations. A Km of 0.044% apple pectin and a Vmax of 9.52 units g−1 DM were obtained for one specific enzyme extract.