Survival and growth of Listeria monocytogenes in lubricants used in the food industry

The survival and growth of three Listeria monocytogenes strains in 10 lubricants (synthetic and mineral-oil based) used in the food industry, and rapeseed oil, was investigated at room temperature (20 °C) and refrigerated (5 °C). Additionally, the transfer of L. monocytogenes from lubricants to stainless steel surfaces and vice versa was investigated. Though the amount of L. monocytogenes in most lubricants, both pure and soiled, decreased significantly (p < 0.05) during the 14 d test period, lubricants may act as sources of contamination on the basis of the results obtained on the survival of L. monocytogenes. In general, temperature had significant effect (p < 0.05) on listericidal effect of lubricants contrary to soiling (p > 0.05), however the effect of both factors was dependent on lubricant (p < 0.05). The results clearly showed that L. monocytogenes survived in synthetic conveyer belt lubricant diluted in water. In addition, L. monocytogenes was transferred significantly (p < 0.05) from stainless steel surfaces into conveyer-belt lubricants and into mineral-oil based hydraulic oil.