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

Abstract

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.