Abstract: Fermented rice-chili, a fermented product produced by lactic acid bacteria in southwest China, is produced by anaerobic fermentation of a mixture of crushed fresh red chili, rice flour, salt and other ingredients for a certain time. Chili, rich in polyphenols, may release bound polyphenols during fermentation. Thus, antioxidant activity of fermented rice-chili in cells and its effect on lipid peroxidation in the liver of mice were studied. Results showed total reducing power and oxygen radical absorbance capacity (ORAC) of fermented rice-chili reached their maximum value at 15 and 60 d, respectively. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity of fermented rice-chili at 15 d was higher but not significantly than at 60 d (P > 0.05). However, fermented rice-chili at 15 d showed significantly lower (P < 0.05) inhibitory effect on lipid peroxidation in the liver than at 60 d. Fermented rice-chili at 60 d had significantly lower (P < 0.05) carbonyl content than the control + AAPH group, and its percentage inhibition against bovine serum albumin (BSA) oxidation was 2.38 times as high as that at 15 d. For hemolysis delay time, the sample at 15 d declined faster than that at 60 d with the difference being not significant, and the longest hemolysis delay time was achieved at 0.5 mg/mL. Polyphenol content and percentage inhibition against BSA oxidation were positively correlated (P < 0.01). The antioxidant capacity of fermented rice-chili in cells could be increased by increasing fermentation time, but polyphenol content was not enough to estimate the cellular antioxidant capacity. These data suggest that chemical antioxidant tests in vitro alone are not enough to evaluate antioxidant capacity, and comprehensive evaluation of food antioxidant properties using a cell model can give more objective judgment.

Key words: fermented rice-chili, antioxidant effect, percentage inhibition against oxidation, erythrocyte hemolysis, liver lipid peroxidation