Inactivation of Listeria monocytogenes Scott A on artificially contaminated frankfurters by high-pressure processing

Vacuum-packaged frankfurters, inoculated with 24-h cultures of Listeria mon ocytogenes Scott A (similar to 10(9) CFU/ml) by injection into the packages , were held at pressures of 300, 500, and 700 MPa for up to 9 min. L. monoc ytogenes were washed from the surface of the frankfurter and plated onto br ain heart infusion agar. During the time to achieve 300, 500, and 700 MPa ( come-up time), L. monocytogenes populations decreased by 1, >3, and >5 logs , respectively. Additional inactivation of L. monocytogenes occurred while the samples were held at 300 and 500 MPa. A 5-log reduction in bacterial po pulation was possible at all pressure treatments; however, pressurization a t 700 MPa showed the fastest inactivation with L. monocytogenes reduced fro m 10(8) to 10(2) CFU/package during the come-up time. These results show th at high-pressure processing may be a viable method for controlling foodborn e pathogens in postprocessed, packaged frankfurters.