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

Abstract

Vacuum-packaged frankfurters, inoculated with 24-h cultures of Listeria monocytogenes Scott A (~109 CFU/ml) by injection into the packages, were held at pressures of 300, 500, and 700 MPa for up to 9 min. L. monocytogenes were washed from the surface of the frankfurter and plated onto brain 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 population was possible at all pressure treatments; however, pressurization at 700 MPa showed the fastest inactivation with L. monocytogenes reduced from 108 to 102 CFU/package during the come-up time. These results show that high-pressure processing may be a viable method for controlling foodborne pathogens in postprocessed, packaged frankfurters.