Abstract: The antioxidant activity in vitro and inhibitory effect of rosemary extract on lipid and protein oxidation in salami were assessed. The total phenol content of rosemary extract was measured, and its 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect, the oxygen radical absorbance capacity (ORAC) and reducing power were investigated. The effect of adding different amounts of rosemary extract to salami on the content of thiobarbituric acid reactive substances and total protein thiol content was addressed during salami processing. The results showed that the total polyphenol content of rosemary extract was 197.6 mg/g. Rosemary extract at concentrations greater than 80 μg/mL possessed higher DPPH radical scavenging activity than sodium D-isoascorbate (P < 0.05). Its ORAC was 2 920.3 μmol Trolox/g, which was significantly higher than that (1 746.9 μmol Trolox/g) of sodium D-isoascorbate (P < 0.05). There was no significant difference in reducing power between rosemary extract at a certain concentration and sodium D-isoascorbate (P > 0.05). The addition of rosemary extract at 0.02% or 0.03% could more effectively inhibit lipid oxidation in salam than sodium D-isoascorbate at 0.02% (P < 0.05). The addition of rosemary extract at 0.03% showed significant inhibitory effect on protein oxidation and the effect was comparable to that at 0.02% (P < 0.05) . This experiment confirmed that rosemary extract has good antioxidant activity in vitro and as an efficient free radical scavenger and natural antioxidant, it can significantly inhibit lipid and protein oxidation during the processing of salami.

Key words: rosemary extract, antioxidant activity, salami, lipid oxidation, protein oxidation