Presence of Listeria monocytogenes in Prepared Foods: Analysis of Influencing Factors

• Published in: Journal of food processing and preservation Vol. 41; no. 2; pp. np - n/a
• Main Authors: Benito, S., López, A., Lizana, X., Lope, S., Carbó, R., Valle, L.J., Marqués, A.M., Piqué, N.
• Format: Journal Article Publication
• Language: English
• Published: 01.04.2017
• Subjects: Bacteria; Biologia; Ciències de la terra i de la vida; Contamination; Cuina preparada amb antelació; Enginyeria agroalimentària; Enrichment; Enterobacteriaceae; Foods; Ingredients; Listeria; Listeria Monocytogenes; Listeriosis; Restoration; Àrees temàtiques de la UPC; ANE, Spain
• ISSN: 0145-8892; 1745-4549; 1745-4549
• DOI: 10.1111/jfpp.12842

Although food‐borne outbreaks of listeriosis are uncommon, they remain a major public health problem. We assessed the prevalence of Listeria monocytogenes in prepared foods and the influence of different factors (including type of food or presence of accompanying bacteria). Results showed that accompanying bacteria cause interference in the sensitivity of the detection method, being half Fraser the enrichment medium of choice. In 2760 samples, the global prevalence of L. monocytogenes was 1.4%. In ready‐to‐eat foods, the highest prevalence (23.3%) was found in products containing fermented or cured ingredients and the prevalence was also higher in foods with high counts of aerobic bacteria and lactose‐positive Enterobacteriaceae, two indicators of process hygiene. We also found that foods stored in <0C had a higher prevalence (4.1%) of L. monocytogenes. In prepared foods, factors favoring the presence of L. monocytogenes could be some components of ready‐to‐eat foods, temperatures <0C, and presence of accompanying bacteria. Practical Applications Results are of relevance for practical application as this study was performed in the context of the routine practice of a food control company, with samples collected in different restoration centers from Spain. Results obtained have allowed identifying some factors favoring the presence of L. monocytogenes, which should be taken into account in the current practice of the manufacturing centers of prepared foods to avoid contamination by this bacterium. Based on our results, actions aimed at avoiding high numbers of accompanying bacteria as aerobic mesophilic bacteria (AMB) or Enterobacteriaceae should be taken into account. Special care should also be taken in the manufacturing of foods containing fermented or cured ingredients, as cheese. Finally, the manufacturing centers should also consider the risk of Listeria contamination due to the use of sophisticated machinery or due to the storage of prepared foods at temperatures <0C.