A. Khojasteh et Ea. Murano, INABILITY OF HEAT-STRESS TO AFFECT SENSITIVITY OF LISTERIA-MONOCYTOGENES TO PEDIOCIN IN PORK, Journal of food safety, 16(3), 1996, pp. 201-208
The effect of heat-shock (48C for 20 min) on sensitivity of Listeria m
onocytogenes Scott A to bacteriocin produced by Pediococcus acidilacti
ci was evaluated. Exposure of Listeria to pediocin (68, 267AU/mL) resu
lted in lower number of survivors in the first 2 h of incubation in Tr
ypticase soy broth at 37C compared with samples without pediocin, rega
rdless of whether the cells were heat-shocked or not. Further incubati
on for 24 h resulted in resumption of growth by L. monocytogenes, with
counts reaching the same level as samples without pediocin. Cold stor
age of Listeria in pork in the presence of pediocin (8, 192 AU/g) resu
lted in a 2.0 log(10) reduction after 24 h, when compared with control
s not exposed to pediocin, regardless of whether the samples were stor
ed under air, vacuum, or a modified atmosphere. Prior heat-shocking di
d not have an effect on sensitivity of Listeria to pediocin during sto
rage. Thus, storage atmosphere and exposure to heat shock, which are k
nown to induce thermotolerance in L. monocytogenes, had no effect in s
ensitivity of this organism to pediocin.