The occurrence of Listeria monocytogenes in retail ready-to-eat meat and poultry products related to the levels of acetate and lactate in the products

Abstract

Listeria monocytogenes is a psychrotrophic foodborne pathogen that has been isolated from ready-to-eat meat and poultry products (RTE meats). The purpose of this study was to quantify lactate and acetate levels in retail RTE meats that had been tested in a previous study for the presence of L. monocytogenes to correlate the occurrence of L. monocytogenes to the acid levels. Products were extracted after blending 50 g of each sample with de-ionized water, and the extracts were quantified for lactate and acetate using HPLC. In general, the concentrations of both acids in samples varied with product types and manufacturers (p < 0.05). The mean concentrations of lactate and acetate ranged from 10.71 to 23.03 mg/g (1.07–2.30%) and 0.66–1.56 mg/g (0.066–0.156%), respectively. The mean concentrations of lactate and acetate in L. monocytogenes-positive samples were 1.13–24.05 mg/g (0.11–2.4%) and 0–5.74 mg/g (0–0.574%), respectively. Results of this study indicate that RTE meats containing low levels of lactate were more likely to be positive for L. monocytogenes while samples with higher concentrations of lactate and acetate were less likely to be positive for the pathogen. Therefore, the addition of lactate and acetate as antimicrobials is helpful as part of an overall Listeria control program. However, a rigorous sanitation and an effective HACCP program are also essential for control of Listeria.