Inhibitory effects of pepper (Zanthoxylum bungeanum Maxim) leaf extract on lipid and protein oxidation during the processing of Chinese traditional dry-cured meat (larou)

This study investigated the antioxidant properties of pepper (Zanthoxylum bungeanum Maxim.) leaf (ZL) extract as a natural oxidative agent against lipid and protein oxidation during larou processing. The phenolic profile of the ZL extract was assessed by HPLC and the ZL extract exhibited high 2,2 diphenyl-1-picryl-hydrazyl (DPPH) (0.46 +/- 0.07 mg mL(-1)) and 2,-2'-azino-di-(3-ethylbenzothiazoline sulfonic acid (ABTS) (0.38 +/- 0.04 mg mL(-1)) radical scavenging activity. The lipid and protein oxidation of larou was evaluated during the whole process with 0.02%, 0.04%, and 0.06% ZL extracts. Results showed that larou incorporation with ZL extracts significantly delayed the formation of thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and peroxide values (POV), and carbonyls (P < 0.05). In contrast, the surface hydrophobicity and intrinsic tryptophan fluorescence intensity were decreased (P < 0.05). Meanwhile, we found that the deceleration of sulfhydryl and protein solubility loss was observed in a concentration-dependent manner (P < 0.05). Moreover, owing to the inhibitory effect of ZL extracts on lipid and protein oxidation, the sensory qualities of larou were improved during processing with increasing concentrations of ZL extract. These results suggested that ZL extract has huge prospects for application in dry-cured meat processing.