Effects of stabilization combined with fermentation treatments on the volatile composition and flavor profile of cooked black rice

Superheated steam (SS) or far infrared radiation (FIR) stabilization combined with solid-state fermentation were applied to improve the flavor profile of cooked black rice. E-nose data showed that different cooked black rice samples had similar flavor profiles, and fermentation increased volatiles contents. Besides, a total of 84 volatiles were identified by HS-SPME-GC-MS, and cooked rice of single fermented black rice (FBR) showed the highest total content of volatiles, while cooked rice of fermented FIR stabilized black rice (FSBR-FIR) had the richest varieties of volatiles. Furthermore, 21 out of 84 volatiles were screened as key volatiles by odor activity value (OAV) analysis. Afterwards, naphthalene, nonanal, indole, (E, E)-2, 4-decadienal, eugenol, 2-pentylfuran, (E)-citral, (2E)-2-decenal were screened as differential key volatiles via combination of OAV analysis and partial least squares-discriminant analysis (PLS-DA). It was worth noting that the contents of unpleasant volatiles (indole and eugenol) were the poorest in the cooked rice of FSBR-FIR, while the contents of pleasant volatiles (nonanal, (E, E)-2, 4-decadienal, 2-pentylfuran, and (2E)-2-decenal) were the richest in the cooked rice of FSBR-FIR. The above results suggested that FIR stabilization combined with solid-state fermentation was the most valued to improve the flavor profile of cooked black rice.