Abstract:
Paddy was soaked with 30% moisture, and hot water soaking (35, 40, 45, 50, 55, 60 °C) was compared to
cold soaking (CS) and submerged aerated soaking (SAS) in terms of the parameters of the paddy grain
and the effluent. The investigation demonstrated that hot water soaking yielded the highest total solids
(TS) (1.946±0.045 g/L), total dissolved solids (TDS) (1.724±0.013 g/L), and electrical conductivity (EC)
(2.651±0.039 mS/cm) values. Elevated dissolved oxygen (DO) (3.72±0.04 mg/L) was observed in the hot
water soaking (60 °C) due to the reduction of soaking duration (2 h). By contrast, the SAS maintained a
nearly neutral pH (7.35±0.01) and lower turbidity (510.0±1.4 NTU) level compared to the hot water
soaking. The leaching rates and moisture absorption were computed using Pseudo-second-order and Peleg
models, and a higher leaching rate (0.081 g/L min) was detected at 60°C. The SAS produced higher
efficiency with less resource consumption by reducing effluent strength while maintaining TS in paddy
grains. The new knowledge created by the comprehensive evaluation CS, SAS, and hot water soaking of
paddy parboiling using leaching models and paddy hydration adds new insights to the development of
efficient paddy parboiling methods.
