Predictive Modelling of Peroxidase, Polyphenol Oxidase and Catalase in Post-Harvest White Trifoliate (D. Dumetorum Var.) Yam Tubers

Abstract

The enzymes peroxidase (EC 1.11.1.7), polyphenol oxidase (EC 1.10.3.1) and catalase (EC 1.11.1.6) are fundamental in the development of Dioscorea dumetorum yam tissues. Enzymological studies on activities of peroxidase, polyphenol oxidase and catalase in white trifoliate yam tubers stored for three (3) days under room temperature (28±2°C) and 72-85%RH, and at refrigeration (5±1°C) and 85-100%RH conditions were fitted in a second order polynomial model. The model showed that at day three (3) of yam storage, a 750units activity of peroxidase relates to 1200units of polyphenol oxidase activity in white trifoliate yam tubers stored at 28±2°C and 72-85%RH. Similarly, day three (3) of yam storage, a 7.5 units of catalase activity relates to 1000units of peroxidase activity in white trifoliate yam tubers stored at 28±2°C and 72-85%RH. Also, day three (3) of yam storage, a catalase activity of 2 units corresponded to 400 units for both peroxidase and polyphenol oxidase activities in white trifoliate yam tubers at 5±1°C and 85-100%RH. This data describes the mechanism of association of these enzymes as may be linked to the production of biomolecules that affect biochemical changes and physical properties in post-harvest white trifoliate yam tuber.