Relationship of Moisture Content Gradients and Glass Transition Temperatures to Head Rice Yield during Cross-Flow Drying

A single kernel approach was taken in this study to investigate cross-flow drying of rough rice in a pilot-scale dryer with regard to the relationship of kernel moisture content gradients and glass transition temperature to head rice yield trend during drying. Individual kernel moisture content distribution and its standard deviation at various drying durations and different locations across the drying column were measured using a single kernel moisture meter. The drying behaviour of rice kernels was mapped onto a glass transition state diagram of rice and related to head rice yield variations during drying. It was found that at different locations in a dryer, rice drying took place in different regions of the glass transition state diagram. The drying behaviour and head rice yield trend could be explained well using the concepts of maximum moisture content gradient time obtained by finite element simulation combined with the glass transition temperatures of rice kernels.