A heat and mass transfer model based on multi-component heterogeneity for corn kernel tempering drying: Development and application

A 3D mathematical model for corn tempering drying was developed by considering the thermo-physical heterogeneity of different components in corn kernels. Simulated results were in good agreement with the experimental results measured by magnetic resonance imaging (MRI) and infrared thermal imaging. Corn germ showed a higher moisture and lower temperature region. The germ and hard endosperm were the source of moisture transfer in corn kernels during tempering. There was an increasing demand of corn kernels for tempering intensity with the growth of tempering drying stage. The optimized multi-stage tempering drying with variable time parameters (OTD) shortened the drying time by 24.5% and 5.63% compared with continuous drying (CD) and multi-stage tempering drying with 30 min tempering and 30 min drying (TD), respectively. In addition, the moisture gradient and temperature gradient of endosperm were at lower levels during drying stages, which was beneficial to avoid cracks caused by the wet-thermal stress.