The influence of metal ions on the dielectric enhancement and radical generation of rice starch during microwave processing.

In this study, the effect of the enrichment of rice starch with metal ions on its capability to generate free radicals during microwave processing was investigated. The underlying mechanism was explored from two aspects: dielectric and thermal properties. Rice starch was modified with ions of iron, copper, manganese and calcium. The modified starches were analyzed in terms of dielectric properties, activation energy (Ea) and thermodynamic characteristics of gelatinization. The quantity and character of the free radicals were analyzed using electron paramagnetic resonance (EPR). The results showed that the metal ions could change the dielectric property and inter structure of rice starch, thus influencing the ability of rice starch to generate radicals under microwave irradiation.