Randy Chandler
Listeria, a common bacterium, can cause a potentially fatal illness called listeriosis. Listeria is a food-borne infection that can spread through many foods, including meat, poultry, seafood, dairy, and produce. Soft cheeses, such as feta, are particularly susceptible to listeria contamination. Feta cheese, a soft, surface-ripened cheese, is often consumed raw, which poses a higher risk of listeria infection. While healthy individuals rarely suffer severe illness from listeria, it can be deadly for unborn babies, newborns, and those with weakened immune systems. Therefore, it is crucial for pregnant women and individuals with compromised immune systems to exercise caution when consuming soft cheeses like feta.
| Characteristics | Values |
|---|---|
| Is listeria common in feta cheese? | Yes, listeria bacteria can be found in feta cheese. |
| Which type of cheese is most susceptible to listeria? | Soft, semi-soft, or surface-ripened soft cheese (such as feta, brie, camembert, ricotta, and roquefort) is most susceptible to listeria. |
| What are the risks of consuming feta cheese with listeria? | Listeria can cause a potentially serious illness called listeriosis. Listeriosis can be very serious for pregnant women, people older than 65, and people with weakened immune systems. |
| How to prevent listeria infection from feta cheese? | Feta cheese used in cooked dishes is considered safer than consuming it raw. Cooking at high temperatures can help eliminate bacteria, including listeria. |
| What are other foods susceptible to listeria? | Deli meats, meat spreads, hot dogs, smoked seafood, and raw vegetables. |
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What You'll Learn
Listeria in feta cheese during the manufacturing process
Listeria monocytogenes is a well-known foodborne pathogen that can cause serious illness, especially in pregnant women, people over 65, and those with weakened immune systems. It can be found in various foods, including soft cheeses such as feta.
During the manufacturing process of feta cheese, Listeria monocytogenes can be introduced through contaminated milk or brine. In one study, pasteurized whole cow's milk was inoculated with Listeria monocytogenes and made into feta cheese according to standard procedures. The fresh cheese was then placed in sterile salt brine and held at specific temperatures for several days before being stored at 4°C. Throughout the process, the milk, curd, whey, cheese, and brine were tested for the presence and growth of Listeria monocytogenes.
Listeria monocytogenes can survive and grow during the feta cheese-making process, ripening, and storage. The bacteria can become entrapped in the curd during cheese-making, with a higher population in the curd than in the inoculated milk. During ripening, the number of Listeria monocytogenes can increase further, and both strains of the bacteria (Scott A and California) have been found to survive in feta cheese for more than 90 days, even at low pH levels.
The growth potential of Listeria monocytogenes in feta cheese-based sauces has also been studied. When contaminated with Listeria monocytogenes, these sauces were stored aerobically at 4°C for 30 days. It was found that the growth potential of the bacteria was calculated at -1.2 log CFU/g for the 30-day shelf life, and the addition of sorbic acid as a preservative was shown to inhibit the growth of the bacteria.
To mitigate the risk of Listeria contamination in feta cheese, measures such as gamma-irradiation have been tested. While irradiation doses of 1.0, 2.5, and 4.7 kGy did not eliminate Listeria monocytogenes, the highest dose reduced the viable population to a level compliant with EC regulations. However, it is important to note that the aroma profile of the feta cheese was temporarily affected at the highest dose, returning to normal after 30 days of cold storage.
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Listeria in feta cheese during ripening
Listeria is a bacterial illness that can be very serious for pregnant women, people over 65, and those with weakened immune systems. It can be contracted by consuming tainted raw vegetables, meat, raw milk, or foods made with unpasteurized milk, such as soft cheeses. Feta cheese is a type of soft cheese that has been identified as a potential source of listeria contamination.
The presence and survival of Listeria monocytogenes in feta cheese during the manufacturing, ripening, and storage processes have been the subject of several studies. One study found that Listeria monocytogenes can become entrapped in the curd during the cheese-making process, resulting in a higher population of the bacteria in the curd compared to the inoculated milk. During the first two days of ripening, the number of Listeria monocytogenes increased significantly, with a maximum count of 1.5 x 10^6 cfu/g. Even after ripening, when the pH of the feta cheese dropped to 4.30, both strains of Listeria monocytogenes survived for more than 90 days.
Another study examined the growth potential of Listeria monocytogenes in a ready-to-eat feta cheese-based sauce stored at 4°C. The results indicated that the sauce was unable to support the growth of Listeria monocytogenes when contaminated with low numbers of the bacteria. However, it is important to note that Listeria monocytogenes may still pose a serious threat to the microbiological safety of feta cheese-based products due to its ubiquitous nature and ability to grow under refrigeration.
To minimize the risk of Listeria infection, it is recommended that individuals, especially those who are pregnant or immunocompromised, avoid consuming soft cheeses, including feta cheese, unless they are made with pasteurized milk. Proper food handling and storage practices are also important to prevent contamination and the growth of Listeria bacteria.
Overall, the presence of Listeria monocytogenes in feta cheese during the ripening process is a concern, and further research and safety measures are necessary to mitigate the risk of Listeria infection associated with the consumption of this cheese.
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Listeria in feta cheese during storage
Listeria monocytogenes is a foodborne pathogen that can cause listeriosis, a serious illness that can be fatal to unborn babies, newborns, and people with weakened immune systems. Soft cheeses, deli meats, and unpasteurized dairy products are particularly susceptible to contamination by Listeria bacteria. Feta cheese is a soft cheese that has been identified as a potential source of Listeria infection.
During the feta cheese-making process, Listeria monocytogenes can become entrapped in the curd, resulting in higher populations of the bacteria in the curd compared to the milk used in cheese production. The growth of Listeria monocytogenes in feta cheese has been observed during the first two days of ripening, with the population increasing by approximately 1.5 Log10 cfu/g. Even after ripening, when the pH of feta cheese decreases to 4.30, both strains of Listeria monocytogenes (Scott A and California) have been found to survive in feta cheese for more than 90 days.
The survival of Listeria monocytogenes in feta cheese during storage is a significant concern. One study examined the growth potential of Listeria monocytogenes in a ready-to-eat feta cheese-based sauce stored at 4°C for 30 days. It was found that the organism did not exceed 100 CFU/g by the end of the product's shelf life, even when contaminated with low initial numbers of the bacteria. However, another study found that Listeria monocytogenes can survive in feta cheese for extended periods, even at low temperatures of 4°C.
To reduce the risk of Listeria infection, it is recommended that pregnant women, individuals over 65, and those with weakened immune systems avoid consuming soft cheeses, including feta cheese, unless they are made with pasteurized milk. Proper storage and handling of feta cheese are also crucial to minimizing the risk of Listeria contamination.
Overall, the presence of Listeria monocytogenes in feta cheese during storage is a concern, particularly for vulnerable populations. While the growth potential of the bacteria in feta cheese-based products may be limited by factors such as preservatives and storage temperature, the survival of Listeria monocytogenes for extended periods highlights the need for caution when consuming feta cheese, especially for individuals at higher risk of infection.
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Listeria in feta cheese sauce
Listeria, or listeriosis, is a foodborne illness caused by bacteria that can spread through many foods. Listeria bacteria can be found in soil, water, animal waste, raw vegetables, tainted meat, raw milk, and foods made with unpasteurized milk. It can also be found in certain processed foods such as soft cheeses, hot dogs, and deli meats. While healthy people rarely become very ill from listeria infection, the disease can be fatal to unborn babies, newborns, and people with weakened immune systems.
Feta cheese is a type of soft cheese that has been associated with listeria contamination. While most commercially available feta cheeses are pasteurized, it is essential to verify by checking the label on the packaging. Feta cheese used in cooked dishes, such as baked pasta or casseroles, is considered safer than consuming it raw. Cooking at high temperatures can help eliminate bacteria, including Listeria.
The presence of Listeria monocytogenes in feta cheese-based sauce has been the subject of research. One study found that Listeria monocytogenes may pose a serious threat to the microbiological safety of ready-to-eat (RTE) cheese-based sauces, such as feta cheese sauce. The growth potential of Listeria monocytogenes in feta cheese-based sauce stored at 4°C for 30 days was calculated to be -1.2 log CFU/g for the 30-day shelf life. However, it was concluded that the sauce containing 900 ppm of sorbic acid as a preservative was unable to support the growth of Listeria.
Another study examined the survival of Listeria monocytogenes in frozen ewe's milk and feta cheese curd. It was found that both strains of L. monocytogenes survived in feta cheese for more than 90 days even at low pH levels. Additionally, Listeria monocytogenes was found to be entrapped in the curd during the cheese-making process, with higher populations in the curd than in the inoculated milk.
To reduce the risk of listeria infection, it is important to practice safe food handling and storage practices. This includes washing and drying hands thoroughly before and after handling and preparing food, as well as refrigerating leftovers immediately and using them within a few days. It is also recommended to reheat leftovers to steaming hot (at least 75°C) before consuming. For those who are pregnant, have a weak immune system, or are in a vulnerable state of health, it is crucial to take extra precautions and avoid foods that are more likely to be tainted by listeria.
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How to avoid listeria during pregnancy
Listeria is a foodborne illness that can be very serious for pregnant women. It can be transmitted to the unborn baby, and can even be fatal. While the risk of contracting the infection from day-to-day eating is extremely low, it is still important to take precautions to ensure the safety of both mother and baby. Here are some ways to avoid listeria during pregnancy:
Avoid High-Risk Foods
Certain foods are known to pose a higher risk of listeria transmission. These include soft cheeses such as feta, brie, Camembert, blue cheese, queso fresco, and cotija. Deli meats, hot dogs, and processed meats are also high-risk foods. It is best to avoid these altogether during pregnancy, but if you do consume them, make sure to heat them to 165° F (74° C). In addition, avoid raw or undercooked meats, sushi, and unpasteurized dairy products.
Cook Foods Thoroughly
To kill any potential listeria bacteria, cook all foods thoroughly. Use a food thermometer to ensure that foods reach an internal temperature of 165° F (74° C). This is especially important for pregnant women, as undercooked foods can harbour dangerous bacteria.
Wash and Cook Leafy Greens
Leafy greens, such as spinach, kale, and collard greens, can be contaminated with listeria from irrigation water or animals. Wash these vegetables thoroughly before consumption, and consider cooking them to reduce the risk of infection.
Avoid Cross-Contamination
Listeria can survive on surfaces such as knives, cutting boards, and countertops. Avoid cross-contamination by washing your hands and surfaces frequently, especially after handling raw meat or eggs. Keep raw foods separate from ready-to-eat foods to prevent the spread of bacteria.
Practice Good Food Safety
Stay informed about food recalls and avoid consuming foods that have been recalled due to listeria contamination. Check expiration dates and practise safe food storage to reduce the risk of eating contaminated foods. Wash your hands before handling food and after handling raw meats.
By following these precautions, you can significantly reduce your risk of contracting listeria during pregnancy and protect both your health and that of your unborn child.
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Frequently asked questions
Listeria is a common bacterium that can cause a potentially serious illness called listeriosis.
Feta cheese is a soft cheese that is susceptible to Listeria contamination. Listeria monocytogenes can grow during the feta cheese-making process and survive during ripening and storage.
Listeria infection during pregnancy can lead to serious complications, including miscarriage, stillbirth, premature delivery, and infant death. It can also cause health problems in newborns, such as low birth weight and meningitis.
To reduce the risk of Listeria infection from feta cheese, it is recommended to cook it thoroughly at high temperatures. Feta cheese used in cooked dishes, such as baked pasta or casseroles, is considered safer than consuming it raw.
In addition to soft cheeses like feta, Listeria can be found in raw vegetables, tainted meat, raw or unpasteurized milk, processed meats, and smoked seafood.
