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Published on: May 6, 2013
Assessing the Listeria monocytogenes transference during mechanical slicing of mozzarella cheese
Paula Marques Rivas1, Danielle Carmo da Silva2, Stefani Machado Lopes2
1Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul (ICBS/UFRGS), Av. Sarmento Leite, 500, Sala 210, Centro, CEP. 90.050-170, Porto Alegre, RS, Brazil.
Abstract:
Listeriosis is a foodborne disease caused by Listeria monocytogenes (LM) and has been linked to the consumption of sliced mozzarella cheese. This study aimed to assess the LM transference during mechanical slicing of mozzarella cheese and its growth during refrigerated storage. Mozzarella cheese was contaminated with LM and 100 slices containing approximately 5 log CFU/slice were produced. Next, 100 slices of non-contaminated cheese were sliced using a contaminated blade (3.67log CFU/10 cm2). LM was quantified on the blade and slices right after slicing and after storage at 10 °C for 10 and 15 days. Results demonstrated that increasing counts of LM were transferred to the blade, comparing the first and the fifth slices (2.71 and 3.22log CFU/10 cm2, respectively, p ≤ 0.05), however, transference stabilized after the 50th slice (3.75 CFU/10 cm2). The blade transferred 1.69-2.66 log CFU/g of LM to different slices. At the end of the storage at 10 °C by 10 and 15 days, LM counts increased to 1.51 and 1.69 log CFU/g, respectively, indicating that LM population can increase if the cheese is stored for a long time.
Insights
Listeria monocytogenes (LM) can transfer from contaminated blades to mozzarella cheese slices during mechanical slicing. This pathogen can also grow during refrigerated storage, posing a food safety risk.
Area of Science:
- Food Microbiology
- Food Safety
- Bacterial Pathogenesis
Background:
- Listeriosis, a serious foodborne illness, is often caused by Listeria monocytogenes (LM).
- Consumption of contaminated sliced mozzarella cheese has been implicated in listeriosis outbreaks.
- Understanding LM contamination and growth in cheese is crucial for public health.
Purpose of the Study:
- To evaluate the transference of LM from a mechanical slicer blade to mozzarella cheese slices.
- To determine the growth of LM on sliced mozzarella cheese during refrigerated storage.
- To assess the risk of LM contamination during cheese processing and storage.
Main Methods:
- Mozzarella cheese slices were artificially contaminated with LM.
- Non-contaminated cheese slices were processed using a blade with a known LM contamination level.
- LM levels were quantified on the blade and slices immediately after slicing and after 10 and 15 days of refrigerated storage at 10°C.
Main Results:
- LM was transferred from the contaminated blade to the cheese slices, with transference increasing on initial slices and stabilizing thereafter.
- The blade transferred significant levels of LM (1.69-2.66 log CFU/g) to the cheese.
- LM populations increased during refrigerated storage, reaching 1.51 and 1.69 log CFU/g after 10 and 15 days, respectively.
Conclusions:
- Mechanical slicing can effectively transfer LM to mozzarella cheese.
- Refrigerated storage, even at 10°C, allows for LM proliferation on contaminated cheese.
- This study highlights the importance of stringent hygiene practices in cheese slicing and appropriate cold chain management to mitigate listeriosis risk.
