MICROBIAL SAFETY OF SUPERCRITICAL CARBON DIOXIDE PROCESSES

The effect of supercritical CO2(SC‐CO2) processes on the population of Escherichia coli and Staphylococcus aureus was determined in both phosphate buffer solution and ground beef systems at 35, 42.5 and 50C/10.34, 20.67 and 31.03 MPa. Higher pressures and temperatures significantly decreased the D‐values of both bacteria. No cells survived at 50C. E. coli was more resistant to SC‐CO2processes than was S. aureus in phosphate buffer solution at 35C and in ground beef at 42.5C. After applying SC‐CO2at 35C for 1 h in a phosphate buffer solution, pH values dropped from 6.6–6.8 to 3.7–3.9 at each pressure and remained relatively constant at that level for 6 h. While the count of S. aureus recovered completely after 18 h of incubation, under similar conditions E. coli did not.