Listeria monocytogenes inhibition by lactic acid bacteria and coliforms in Brazilian fresh white cheese

Author(s)

Aragon-Alegro, Lina Casale ^[1] ; Lima, Emilia Maria Franca ^[1] ; Palcich, Gabriela ^[1] ; Nunes, Tatiana Pacheco ^[1] ; de Souza, Katia Leani Oliveira ^[1] ; Martins, Cecilia Geraldes ^[1] ; Noda, Patricia Kary ^[1] ; Destro, Maria Teresa ^[1] ; Pinto, Uelinton Manoel ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Pharmaceut Sci, Dept Food & Expt Nutr, Food Res Ctr, BR-05508000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Brazilian Journal of Microbiology; v. 52, n. 2, p. 847-858, JUN 2021.
• Web of Science Citations: 3

Abstract

Introduction Minas fresh cheese (MFC), a Brazilian white cheese, is one of the most popular cheeses nationwide. Studies have shown that Listeria monocytogenes occurrence in this product is generally low, while high populations of coliforms can be found. This study aimed to evaluate the influence of coliforms in the behavior of L. monocytogenes in MFC. Methods Pasteurized milk was inoculated with L. monocytogenes and coliforms, and the acidification was made by lactic acid or by the addition of a starter culture. The cheeses of each production were divided into 3 groups and stored at 5 oC, 12 oC and cycles of 5 oC followed by 25 oC. In predetermined days, samples were taken and L. monocytogenes, coliforms and lactic acid bacteria populations were evaluated, besides the pH, water activity (aw), titratable acidity and NaCl concentration. Results The inhibition of L. monocytogenes in the presence of coliforms was observed (p < 0.05), except for those samples prepared with lactic acid and stored at temperature cycles. The values of pH and aw were not sufficiently low to cause inhibition; however, titratable acidity was higher in cheeses containing coliforms. In vitro tests containing lactic acid and L. monocytogenes showed that the bacterium is sensitive to concentration of lactic acid >= 0.3%, indicating that lactic acid produced by coliforms strongly influences the population of L. monocytogenes. Conclusions Thus, it can be concluded that coliforms negatively impact populations of L. monocytogenes in MFC. We strongly recommend that producers of MFC adopt good hygiene practices to not only avoid contamination with L. monocytogenes, but also coliforms. (AU)

• FAPESP's process: 13/07914-8 - FoRC - Food Research Center
• Grantee: Bernadette Dora Gombossy de Melo Franco
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC