Sage and rosemary essential oils versus BHT for the inhibition of lipid oxidative reactions in liver pâté

The antioxidant effect of two plant essential oils (sage and rosemary essential oils) and one synthetic antioxidant (BHT) on refrigerated stored liver pâté (4 °C/90 days) was evaluated. Pâtés with no added antioxidants were used as controls. Liver pâtés were analysed for the amount of polyunsaturated fatty acids (PUFA), thiobarbituric acid reactive substances (TBA-RS) numbers, and lipid-derived volatiles at days 0, 30, 60 and 90 of refrigerated storage. The amount of PUFA gradually decreased during refrigerated storage of porcine liver pâtés with this decrease being significantly greater (P<0.05) in control and BHT pâtés than in those with added essential oils. Consistently, the increase of TBA-RS numbers during refrigerated storage of liver pâtés was significantly higher in control pâtés than in the treated counterparts. At days 60 and 90, TBA-RS numbers in treated pâtés were significantly smaller (P<0.05) than in the control counterparts. Headspace solid-phase microextraction (HS-SPME) successfully isolated recognized indicators of lipid decomposition (i.e. hexanal, nonanal, hexan-1-ol, oct-1-en-3-ol, deca-(E,Z)-2,4-dienal) from liver pâtés whereas some other volatiles analysed are typical contributors to the overall off-flavour of oxidized liver (i.e. hept-(Z)-4-enal, non-(E)-2-enal, nona-(E,E)-2,4-dienal). The addition of antioxidants significantly (P<0.05) reduced the total amount of lipid-derived volatiles isolated from liver pâtés HS. Plant essential oils inhibited oxidative deterioration of liver pâtés to a higher extent than BHT did.