Kinetics of Orange II Decoloration Catalyzed by Rice Hull Peroxidase

Abstract

Decoloration of Orange II catalyzed by rice hull peroxidase (RPO) was examined for effects incurred through application of horseradish peroxidase (HRP), Arthromyces ramosus peroxidase (ARP), milk lactic peroxidase (LPO) and soybean peroxidase (SPO). The rate of Orange II decoloration increased with RPO content. 90% decoloration occurred within 120 seconds at RPO the concentration of 3.4×10^-7 M. Decoloration rate was maximum near pH 9.0. At 20°C, RPO caused Orange II to fade more quickly than LPO or SPO, though the decoloration rate was the same as for ARP and HRP. Decoloration did not accelerate with any of the four peroxidases (PODs) at high temperature. Between 20°C and 80°C, the rate constant of RPO greatly increased with temperature, being 5 times greater at 60°C than at 20°C and 7 times greater at 80°C. The decoloration rate of Orange II with RPO increased greatly subsequent to storage for 0 minutes and then at 90°C for a period of 150 minutes, the decoloration rate of Orange II remained the same. RPO was found to be the most stable POD at high temperature.