Microwave and water blanching of corn kernels: Control of uniformity of heating during microwave blanching

Corn kernels were blanched in water and by microwave. The blanching efficiency was measured by four parameters; the thermolability of soluble peroxidase (POD), of two insoluble isoforms (membrane-bound and cellulose-bound POD) and of soluble protein. Using a water-shield model to improve the uniformity of heating by microwave and to control the rate of heating, microwave blanching was significantly more efficient as measured by all four parameters when blanched at 85C. There was no significant difference in the POD isoform heat-stability when blanched at 70C by the two methods. POD insoluble isoforms were more heat-stable than the soluble isoform. POD isoforms, occupying three cellular environments were more efficiently inactivated by uniform microwave heating compared to water blanching, demonstrating the viability of microwave blanching.