Abstract: The synergistic effect of combinations of rosemary extract (0.01 g/g pro) and NaCl at different concentrations on the structure and gel properties of myofibrillar proteins from pork Longissimus dorsi muscle was investigated by determining intrinsic fluorescence intensity, sulfhydryl group content, gel strength, water-holding capacity and rheological properties. The results indicated that addition of rosemary extract did not benefit the formation of stable gel network structure and decreased the water-holding capacity of myofibrillar proteins at NaCl concentration below 0.45 mol/L. However, the combination of rosemary extract and NaCl at 0.45 mol/L could significantly improve the gel strength, storage modulus and water-holding capacity and result in a remarkable decrease in the intrinsic fluorescence intensity of myofibrillar proteins as manifested by a 2 nm red shift. The tertiary structure of myofibrillar proteins changed favorably at lower NaCl concentrations so that the water-holding capacity did not decrease markedly. These results may be expected to provide new insights for the development of salt substitutes.

Key words: NaCl, rosemary extract, myofibrillar protein, protein structure, gel properties