Abstract
Moisture effective diffusivity and glass transition temperature (Tg) of paddy during drying were investigated by drying five varieties of paddy with an initial moisture content of 21.1–24.4% wet basis and a temperature range of 45–70°C in a constant temperature and blast oven. With an increase in drying temperature, the desorption rate and moisture effective diffusivity of paddy kernels increased and drying duration decreased. At a drying temperature of 45°C, the curve of the desorption rate changed slowly and drying duration was longer. Most of the five paddy varieties had similar desorption rates at drying temperatures of 45–70°C, and their moisture effective diffusivities were in the range of 2.638×10−9–2.514×10−8m2min−1 with an active energy of 6.547–36.913kJmol−1. Tg values of long-grain variety ‘Zhunliang you’ and two medium-grain varieties ‘Zhongjia zao’ and ‘Dianjiang’ determined using the differential scanning colorimeter method increased from 38.7°C to 51.2°C when their moisture contents decreased from 20% to 13%. Under similar conditions, differences in Tg values of the three varieties of paddy were observed. When the moisture content of the three varieties of paddy decreases from 20% to 13% at drying temperatures of 50–70°C, drying time should be 60–80minfor less than 10% damage to kernels.
Published Version
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