Effect of natural and synthetic antioxidants on protein oxidation and colour and texture changes in refrigerated stored porcine liver pâté.

The antioxidant effect of two plant essential oils (sage and rosemary) and one synthetic antioxidant (BHT) on refrigerated stored porcine liver pâté (4°C/90 days) was evaluated. Pâtés with no added antioxidants were used as controls. Liver pâtés were analysed for protein oxidation, modification of heme (HI) and non-heme iron (NHI) concentrations, and colour and texture characteristics at days 0, 30, 60 and 90 of refrigerated storage. The amount of carbonyls from protein oxidation significantly (p<0.05) increased during refrigerated storage, and this increase was significantly higher in the control pâtés than in their treated counterparts. Antioxidants successfully protected heme molecules from degradation and significantly inhibited the increase of NHI in refrigerated stored liver pâtés. Colour changes seemed not to be directly related to oxidative processes since pâtés with added antioxidants suffered greater colour modifications than the controls. The addition of rosemary essential oil significantly reduced hardness of liver pâtés. Sage and rosemary essential oils exhibited similar antioxidant properties to BHT denoting their suitability as alternatives to synthetic antioxidants.