Use of Pediococcus acidilactici to Control Listeria monocytogenes in Temperature-Abused Vacuum-Packaged Wieners

Abstract

Pediococcus acidilactici JBL1095 (pediocin AcH producer) and P. acidilactici LB42 (bacteriocin nonproducer) were evaluated for the production of antilisterial compounds in packages of all-beef wieners. Commercially processed, freshly manufactured, unpackaged wieners were surface inoculated (ca. 105 CFU/g) as follows: (i) untreated control; (ii) a three-strain (Scott A, V7, 101M) mixture of Listeria monocytogenes; (iii) strain JBL1095; (iv) L. monocytogenes and strain JBL1095; and (v) L. monocytogenes and strain LB42. Wieners were vacuum packaged and cell numbers, pH, and bacteriocin activity within packages were determined following storage at refrigeration (4°C) or abuse (25°C) temperatures for 72 and 8 d, respectively. L. monocytogenes and pediococci survived in packages held at 4°C, but pediococci did not produce acid or pediocin during refrigerated storage. At 25°C, total numbers of L. monocytogenes (treatment ii) increased 3.2 log10 CFU/g and the pH of the fluid (exudate) within packages increased from 5.5 to 5.6. In contrast, L. monocytogenes survived but did not grow in packages inoculated with strain LB42 (treatment v), and was inhibited (average reduction of 2.7 log10 CFU/g) in packages inoculated with strain JBL1095 (treatment iv) during storage at 25°C for 8 d. The pH of exudate in packages inoculated with strains JBL1095 (treatment iv) or LB42 (treatment v) showed a similar decline (ca. 5.5 to 4.6). The onset of bacteriocin production coincided with early-logarithmic growth of JBL1095 (treatment iv) and continued into the late logarithmic phase. These data suggest that bacteriocinogenic pediococci can be used to control L. monocytogenes in temperature-abused, cook/chili meats.