Modeling and Optimization of Hybrid HIR Drying Variables for Processing of Parboiled Paddy Using Response Surface Methodology

The effects of hot air temperature (40, 50 and 60 °C) and Radiation Intensity (RI) (0.21, 0.31 and 0.41 w/cm^2) on the response variables (drying time, Head Parboiled Rice Yield (HPRY), color value and hardness)) of parboiled rice were investigated. The drying was performed using hybrid hot air–infrared drying. The optimization of drying variables and the relationship between response variables and the influence factors were analysed using response surface methodology (RSM). Based on RSM results, the best mathematical model for prediction of HPRY, hardness and color value and drying time of samples was linear(R^2= 0.96), quadratic(R^2= 0.99), linear(R^2= 0.93) and linear(R^2= 0.99) equation, respectively. The HPRY (62.13- 68.13%) and hardness (130.27- 247.3 N) increased with increasing drying temperature and RI, while the color value (19.77- 18.03) and drying time (59.72- 34.41 min) decreased. The optimized parameters of drying were obtained 55 °C drying temperature and 0.41 w/ cm^2 RI.