Advisor(s)
Abstract(s)
This study estimated the risk of listeriosis from Brazilian cheese consumption using quantitative microbial risk
assessment (QMRA). Risks associated to consumption of two cheese types were assessed: artisanal ripened semihard
cheese (produced with raw milk) and refrigerated fresh soft cheese (produced with pasteurized milk). The
semi-hard cheese model predicted Listeria monocytogenes growth or decline during ripening, while the soft cheese
model predicted pathogen growth during refrigerated storage. Semi-hard cheese modeling scenarios considered
L. monocytogenes starting concentration from −2.4 to 6 log CFU/mL in raw milk and three ripening times (4, 22
and 60 days). Soft cheese modeling scenarios considered L. monocytogenes starting concentration from −2.4 to 4
log CFU/mL in milk. The inclusion of anti-listerial lactic acid bacteria (LAB) in cheeses was also examined. Risk
of listeriosis due to consumption of soft cheese was 6000 and 190 times greater than that of semi-hard cheese, for
general and vulnerable populations, respectively. Aging semi-hard cheese reduced risk, and risk was influenced
by L. monocytogenes starting concentration. Aging cheese with inhibitory LAB for 22 days reduced risk over 4
million-fold when L. monocytogenes was assumed to be 6 log CFU/mL in raw milk. The inclusion of inhibitory
LAB also reduced risk of listeriosis due to soft cheese consumption, but not as much as for semi-hard cheese.
QMRA results predicted that consumption of contaminated cheeses can carry a high risk of listeriosis, especially
for vulnerable populations. Scenario analyses indicated that aging of semi-hard cheese and inclusion of antimicrobial
LAB mix in semi-hard and soft cheeses are effective risk mitigation measures.
Description
Keywords
Dairy products Food inspection Food safety Intervention strategies Natural antimicrobial Traditional foods
Citation
Campagnollo, Fernanda Bovo; Gonzales-Barron, Ursula; Pilão Cadavez, Vasco Augusto; Sant'Ana, Anderson S.; Schaffner, Donald W. (2018). Quantitative risk assessment of Listeria monocytogenes in traditional Minas cheeses: the cases of artisanal semi-hard and fresh soft cheeses. Food Control. ISSN 0956-7135. 92, p. 370-379