Effect of microwave and infrared vacuum drying on physicochemical properties of rice bran and their near infrared spectroscopy (NIR) prediction: partial least square (PLS) and principal component analysis (PCA)

Abstract

Rice bran (RB) stabilized by drying methods at different power, time, and temperature conditions were subjected to be analyzed for chemical compositions and color changes. Compared to unstabilized RB (control), RB stabilized by microwave vacuum drying (at 700 and 800 W for 3 and 4 min) and infrared vacuum drying (at 65 and 70°C for 10 and 15 min) exhibited higher fat, carbohydrate, fiber, a* and b* values, but lower moisture, ash and L* value. Stabilized samples were measured by NIR to obtain spectrum. PCA was used exploratorily to analyze the NIR spectrum showing footprint of rice bran, which indicated a good separation of control and treated samples. The relationship between the NIR spectra and the physicochemical parameters was investigated using PLS. The high values of R² and Q² of the correlation graphs demonstrated that NIR was a good approach for observing the quality change of the processed RB.