Efficacy of marinades against Listeria monocytogenes cells in suspension or associated with green shell mussels (Perna canaliculus).

In order to determine the listericidal efficacies of three marinades used in the production of marinated green shell mussels (Perna canaliculus), decimal reduction times (D values) were determined for a mixture of seven strains of Listeria monocytogenes exposed to marinades in the presence and absence of mussels. With an acetic acid (1.5%, wt/vol) marinade, calculated D values in the presence and absence of mussels were 77.3 and 33.3 h, respectively. Likewise, for an acetic acid (0.75%)-lactic acid (0.75%) marinade and an acetic acid (1.5%)-Glucono Delta-Lactone (0.2%)-based marinade, the D values in the presence and absence of mussels were 125.5 and 26.9 h and 86.3 and 19.3 h, respectively. Various increases in decimal reduction times in the presence of mussels indicated that there was no simple relationship between the listericidal natures of these marinades and the presence of mussels. This result suggests that difficulties may occur in trying to relate acid inhibition studies carried out in model broth systems to "real food" systems.