Kinetic analysis of the thermostability of peroxidase from African oil bean (Pentaclethra macrophylla Benth) seeds

A major problem in the storage and marketing of processed African oil bean seeds is its high deterioration rates due to the undesirable activity of peroxidases. The effect of heat treatment on the activity of peroxidase (POD) from African oil bean (Pentaclethra macrophylla) seeds was studied over a range of 30°C to 80°C. A simple first-order reaction which assumes a biphasic thermoinactivation curves was used to study the denaturation of this enzyme. Results suggested that peroxidase is a stable enzyme with a Z-value as low as 0.0147. This indicates that it is more sensitive to increase in temperature than to the duration of the heat treatment making high temperature short time treatment a technique to be used for its inactivation. The results of the thermodynamic investigations indicated that the oxidation reactions were: (a) not spontaneous (ΔG > 0) for peroxidase at 323oK, and at all the temperatures (2) slightly endothermic (ΔH > 0) at 323 K and (3) reversible (ΔS < 0) at all the temperatures under study.