Drying of Gelatinized Whole Wheat

Whole grains of gelatinized durum and soft wheat were dried by forced and natural convection at 40, 60, 80, and 100°C. Magnetic resonance images taken periodically during drying indicated that Fick's diffusion is not applicable to describe the moisture transfer during drying of the gelatinized wheat grains. A simple mathematical model based on overall moisture balance fitted the experimental data very well. The drying took place in the falling rate period, which was approximated by two regions – first and second falling rate periods (FFRP and SFRP). The internal drying coefficient linearly increased with increasing drying temperature, and was almost an order of magnitude (from 104 to 105 s-1) higher during FFRP than SFRP. The soft wheat dried faster than the durum wheat. The effect of forced convection was more pronounced during FFRP than SFRP.