Optimum Temperature and Thermal Stability of Crude Polyphenol Oxidase from some Common Fruits

Abstract

The effect of temperature on the activity and thermal stability of crude polyphenol oxidase (PPO) extracted from garden egg (Solanum aethiopicum), pawpaw (Carica papaya), pumpkin (Cucurbita pepo), guava (Psidium guajava) and bush mango (Irvingia gabonnensis) fruits were studied using 20 mM Catechol solution as a substrate. The optimum temperature was found to be 30^oC for the enzyme extracted from guava, 40^oC for that extracted from both pawpaw and pumpkin and 50^oC for that from both garden egg and bush mango. The PPO extracted from all the fruits is stable upon incubation for 10 to 120 minutes at temperature between 20- 70^oC. The activity of the crude enzyme from all the fruits used was found to decrease at various degrees after incubation for 10 to 120 minutes at temperature greater than 70^oC. Therefore increasing the incubation temperature above 70^oC would cause decrease in the activity of the enzyme and can be a good method of controlling undesirable changes caused by the enzyme in the products of these fruits.