Impingement drying of germinated brown rice varieties at intermediate temperatures: drying kinetics and analysis of quality

Germinated brown rice is an important source of gamma-aminobutyric acid (GABA). In this study, the impingement drying conditions were carried out at various drying temperatures at air velocity 16 m.s(-1). Impingement drying is an effective technique that accelerates heat transfer and reduces the drying time. Parboiled germinated paddy drying data of two rice varieties were statistically simulated by various drying kinetics modeling. The predicted data using the Midilli drying kinetics model were found to best fit all experimental data. The effective moisture diffusivity (D-eff) of the parboiled germinated paddy varieties was determined by the second Fick's law of diffusion and results showed that the D-eff value increased with the drying temperature. The D-eff value of the short-grain parboiled germinated paddy variety was relatively high compared to the long-grain variety. Chemical quality analysis of biologically active compounds as well as determination of antioxidant activity were carried out. The chemical quality of both rice varieties increased after germination, whilst the steaming and drying processes insignificantly affected it. Our results on impingement drying suggested that the suitable drying temperature was 90 degrees C due to reduction of the drying time, energy saving and causing less chemical disintegration.