Biochemical and structural changes of taro (Colocasia esculenta) tubers during simple thermal treatments (low temperature) or in combination with chemicals.

摘要

The present study set out to study the structural and biochemical modification of taro (Colocasia esculenta) grown in Cameroon, through simple heating or in association with chemicals. Both techniques are known to inactivate the reactions of polyphenol oxidase. The textural analysis was performed on tubers heated in water, 0.5% NaCl and 1% NaCl solution at various times from 0 to 105 min. The result showed optimum pH and temperature for taro polyphenol oxidase (PPO) activity at pH 6.0 and t=40 degrees C with 10 mM catechol in 0.1 M phosphate buffer as substrate. K_m and V_max values were about 7.317+or-0.012 mM and 0.148+or-0.0003 OD_{430 nm}/minute. Seven inhibitors were tested in this study, and the most effective inhibitors were found to be NaCl, CaCl2 and KCl. Kinetic studies showed that the thermal inactivation of taro PPO followed first-order kinetics, with an activation energy of E_a=422.79+or-0.52 kJ/mol. The textural modification of taro tubers during heating follows the kinetic of the fractional model. It was noticed that the activation energy increased with the concentration of NaCl.