Comparative study on physicochemical and nutritional properties of black rice influenced by superheated steam, far infrared radiation, and microwave treatment

The peroxidase in black rice was inactivated by superheated steam (SS), far infrared radiation (FIR), and microwave treatment (Mw) respectively, and then their effects on the physicochemical and nutritional properties of black rice were compared. Results showed that SS, FIR, and Mw completely inactivated peroxidase with minimum time of 16 min, 8 min, 480 s, respectively. FIR and Mw significantly decreased all pasting viscosities and gelatinization enthalpy (ΔH), while SS increased most pasting viscosities and showed almost no influence on ΔH. Besides, black rice stabilized by SS rather than FIR and Mw showed similar cooking and sensory quality and microscopic structure to that of raw black rice. Furthermore, SS was more favorable to retain the phenolics, flavonoids, anthocyanins and antioxidant capacity than FIR and Mw. These results suggested that SS was most suitable to improve the shelf life of black rice with minimal damages to its physicochemical and nutritional properties.