Effect of combined treatment with supercritical CO2 and rosemary on microbiological and physicochemical properties of ground pork stored at 4 °C

The effect of combined treatment with supercritical CO2 (2000 psi, 35 °C for 2 h) and rosemary powder (2.5% and 5.0% (w/w)) on microbiological and physicochemical properties of ground pork stored at 4 °C was investigated. The changes in total viable count, pH, total volatile base nitrogen (TVB-N), lipid oxidation and instrumental color (CIE L⁎, a⁎, b⁎) were analyzed during a week period of refrigerated storage. It was found that microbial populations were reduced by supercritical CO2 treatment, with the more pronounced effect being achieved by combined treatment with supercritical CO2 and 5.0 g rosemary powder/100 g meat. Supercritical CO2 treatment for 2 h could accelerate lipid oxidation of ground pork during refrigerated storage, whereas combination with rosemary can significantly slow down the increase of oxidation rate. Combined treatment of supercritical CO2 and rosemary significantly increased L⁎ and b⁎ values of the ground pork, while the a⁎, pH and TVB-N value were not affected as compared to the treatment with supercritical CO2 alone. The results of this study indicate that combined treatment of supercritical CO2 and rosemary may be useful in the meat industry to enhance the storage stability of ground pork treated with long time exposure of supercritical CO2 during refrigerated storage.