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Advisor(s)
Abstract(s)
Traditional Minas cheeses are very popular in Brazil. These cheeses are of two types: artisanal ripened semi-hard cheeses (HC)
produced with raw milk and refrigerated fresh soft cheeses (SC) generally produced with pasteurized milk.
Purpose: This study estimates the risk of listeriosis due to HC and SC consumption using quantitative microbial risk assessment (QMRA).
Methods: QMRAs were developed for both cheese types. The HC model contained a module for predicting Listeria monocytogenes decline
during ripening. The SC model contained a refrigerated storage module for predicting L. monocytogenes growth during storage. HC modeling
scenarios varied L. monocytogenes starting concentration over -2.4 to 6 log CFU/ml in raw milk and three ripening times (4, 22, and 60 days).
SC modeling scenarios varied L. monocytogenes starting concentration (-2.4 to 4 log CFU/ml in milk). Inclusion of antilisterial lactic acid
bacteria (LAB) was also examined. Simulations (100,000 iterations per scenario) were carried out using the @Risk add-in for Excel.
Results: Aging HC reduced risk, and risk was influenced by L. monocytogenes starting concentration. Aging 22 days with inhibitory LAB
reduced risk more than 4 million-fold when L. monocytogenes was assumed to be 6 log CFU/ml in raw milk, and was lower risk than HC made
without LAB and with a starting concentration of 1 log CFU/ml in raw milk. Inclusion of inhibitory LAB reduced risk of listeriosis from SC, but
not as dramatically as for HC. Relative risk to vulnerable populations reduced 4.4 and 3.4-fold when L. monocytogenes starting concentrations
were 1 log and 4 log CFU/ml in milk, respectively.
Significance: The results of the QMRA predict that consumption of contaminated Minas cheeses can present a high risk of listeriosis,
especially for vulnerable populations. Scenario analyses indicate that aging of HC and inclusion of LAB in HC and SC are effective risk
mitigation measures.
Description
Keywords
Risk assessment of Listeriosis Semi-hard cheeses Fresh soft cheeses
Citation
Campagnollo, Fernanda; Cadavez, Vasco; Gonzales-Barron, Ursula A.; Sant’Ana, Anderson; Schaffner, Donald (2018). Quantitative risk assessment of listeriosis from traditional brazilian minas artisanal semi-hard and fresh soft cheeses. In IAFP 2018 Annual Meeting. Salt Lake City, Utah