Heat-inactivation of mango pectinesterase and polygalacturonase

The present work involves isolation of mango pectinesterase (PE) and polygalacturonase (PG), and investigating some of its characteristics, mainly with respect to heat-stability of the enzymes. Within a reaction time of 10 min, mango PE shows its maximal activity at pH 7.5 in a reaction mixture containing 1% citrus pectin and 0.1 or 0.2 m NaCl, at 55 °C. This enzyme possesses a Z value of 18.5 °C. Mango PG reveals its maximal activity in a reaction mixture containing 0.1% Na-polygalacturonate and 0.1 m NaCl. The reaction mixture was adjusted to pH 4.8 (McIlvaine buffer of 0.1 m) and 30–35 °C. Mango PG was less heat-stable than PE, with a Z value of 12.25 °C. The stepwise running of the inactivation diagrams of PE and PG emphasise the suggestion of the existence of more than one PE and more than one PG in mango enzyme extract.