CONTROL OF LISTERIA MONOCYTOGENES ON FRANKFURTERS WITH ANTIMICROBIALS AND HYDRODYNAMIC PRESSURE PROCESSING*

ABSTRACT

The antilisterial activity of sodium diacetate and pediocin (ALTA 2341) on frankfurters was evaluated in combination with hydrodynamic pressure processing (HDP). Minimum inhibitory concentration (MIC) of these strains as determined in tryptic soy broth was 0.4% and >600 AU/mL, for sodium diacetate and ALTA 2341, respectively. Frankfurters were surface inoculated with a five-strain mixture of Listeria monocytogenes after dipping in (1) control (sterile water); (2) 5% sodium diacetate; (3) 3% ALTA 2341(P1); (4) 6% ALTA 2341 (P2); (5) P1 + sodium diacetate; and (6) P2 + sodium diacetate for 5 min. The frankfurters were vacuum-packaged and treated with hydrodynamic pressure or without HDP. Frankfurters were analyzed at 0, 7, 14 and 28 d for pH, L. monocytogenes (MOX) and aerobic (TSAYE) cell populations during storage at 4C. Antimicrobials and HDP treatment did not change (P < 0.05) the frankfurter pH. HDP treatment significantly reduced (1 log₁₀ cfu/g) L. monocytogenes populations in frankfurters. Dipping treatments containing sodium diacetate or ALTA 2341 did not significantly reduce L. monocytogenes in frankfurters. There was a no synergistic effect between ALTA 2341 and HDP for inhibition of L. monocytogenes. The reduction pattern in aerobic cell populations during storage of antimicrobials and HDP-treated frankfurters was similar to that of L. monocytogenes reduction. These results indicate that the ALTA 2341 preparation was not efficient enough to kill L. monocytogenes. Other antimicrobials should be evaluated in conjunction with HDP treatment for synergistic inhibition of L. monocytogenes during storage at 4C.

PRACTICAL APPLICATIONS

Since the early 1980s, when Listeria monocytogenes was first recognized as an emerging food-borne pathogen, numbers of outbreaks of human listeriosis have been reported. Many of these outbreaks are associated with processed meats. Because of the high mortality rate associated with listeriosis, a zero tolerance approach for L. monocytogenes in ready-to-eat meats and poultry products has been selected by many countries, including the U.S.A. We reported significant L. monocytogenes reduction in frankfurters using hydrodynamic pressure (HDP) treatment. HDP processing using a nonexplosive energy source can be used to reduce L. monocytogenes in frankfurters. While pediocin and organic acids used in our study reduce L. monocytogenes during storage, their practical use is not significant as the reduction is marginal. Other antimicrobials should be evaluated in conjunction with high-pressure processing for required reduction of L. monocytogenes during storage at 4C.