Pregnancy And Cheese: Is Heat Shock Cheese Safe?

During pregnancy, women are advised to be cautious with their food choices due to a weakened immune system. The consumption of certain cheeses is discouraged because of the risk of bacterial growth, specifically listeria, which can cause food poisoning and lead to severe health issues. While pasteurization is recommended to kill harmful bacteria, it can also affect the nutritional content of the cheese. Heat shock cheese, which is heated to a lower temperature than pasteurized cheese, may be a safer alternative for pregnant women. However, it is important to note that the safety of consuming this type of cheese during pregnancy is still a topic of debate, and it is always advisable to consult a healthcare professional for personalized advice.

Pasteurized vs unpasteurized cheese

When it comes to pasteurized vs unpasteurized cheese, there are several factors to consider, including taste, health, safety, and legal regulations.

Pasteurized Cheese

Pasteurized cheese is produced by heating milk to approximately 65° C (149° F) or higher, which kills off pathogenic bacteria that could be harmful. This process is considered more efficient for large-scale production as it requires less care during the milk collection stage, and it also extends the shelf life of dairy products. However, pasteurization can also kill beneficial bacteria that contribute to the unique, complex flavours of some raw milk cheeses. Most of the cheeses available today, especially in Canada, are pasteurized.

Unpasteurized Cheese

Unpasteurized cheese, also known as raw milk cheese, is made by heating milk to a lower temperature of about 30° C (86° F). This temperature allows the milk to start fermenting and eventually become cheese, without destroying the bacterial compounds that give the cheese a more intense flavour. Advocates of raw milk cheese argue that it has been made safely for centuries in Europe, and negative health effects are uncommon. Some industry experts believe that enzymes in raw milk cheese aid digestion and offer additional health benefits.

However, there are safety concerns associated with consuming unpasteurized cheese, particularly for vulnerable individuals such as pregnant women, the elderly, or those with compromised immune systems. In Canada, domestic or imported unpasteurized cheese can be sold but must be aged for at least 60 days to allow any potentially harmful bacteria to die off naturally. This aging requirement also applies to heat-treated cheese, which is made by heating milk to approximately 55° C (131° F) for about 15 seconds, striking a balance between pasteurized and unpasteurized milk.

Heat Shock Cheese

Heat shock cheese refers to a process where the milk is heated to a temperature lower than that used in pasteurization. While it kills off unwanted bacteria, it does not reach the same high temperature as pasteurization. This method is used by some cheese manufacturers, such as Tillamook, as an alternative to pasteurization.

Pregnancy Considerations

During pregnancy, it is recommended to exercise caution when consuming certain types of cheese due to the risk of Listeria contamination, which can cause serious health issues. Soft cheeses with a high moisture content, such as Brie, are particularly susceptible to Listeria growth, even if they are made with pasteurized milk. To ensure safety, pregnant women are advised to cook cheese at high temperatures (above 74° C) until it is completely hot, not just melted.

Heat-treated cheese

In Canada, the rules for selling heat-treated cheese are the same as for unpasteurized cheese. Any cheese made from unpasteurized milk, including heat-treated cheese, must be aged for at least 60 days before being sold. This is because, after this time, any potentially harmful bacteria will have died off naturally.

While heat-treated cheese is generally safe, pregnant women, the elderly, or people with a compromised immune system should still avoid unpasteurized cheese. This is because their immune systems are weaker, and they are more susceptible to listeria, a type of food poisoning that can cause vomiting and diarrhea. Listeria is especially dangerous for pregnant women, as it can lead to miscarriage, stillbirth, or preterm labour.

To be extra cautious, pregnant women can cook their cheese at a high temperature (above 74° C) to kill any bacteria. However, this is not necessary, and most bacteria that cause food poisoning cannot survive above 165° F (about 74° C).

Listeria and listeriosis

Listeria, the bacteria that causes listeriosis, is especially dangerous to pregnant women and their newborns, as well as adults over 65 and people with weakened immune systems. Listeriosis is a serious infection that can lead to miscarriage and stillbirth. It is most commonly caused by eating improperly processed or contaminated food, particularly deli meats and unpasteurized milk products, including soft cheeses.

Listeria monocytogenes (L. monocytogenes) is a species of pathogenic (disease-causing) bacteria that can be found in moist environments, soil, water, decaying vegetation, and animals. It can survive and even grow under refrigeration and other food preservation measures. When people eat food contaminated with L. monocytogenes, they may develop listeriosis.

L. monocytogenes is generally transmitted when food is harvested, processed, prepared, packed, transported, or stored in environments contaminated with the bacteria. Environments can be contaminated by raw materials, water, soil, incoming air, or pets that have eaten contaminated food.

The symptoms of listeriosis range from mild to severe and may last from days to several weeks. Mild symptoms may include fever, muscle aches, nausea, vomiting, and diarrhea. More severe symptoms may include headache, stiff neck, confusion, loss of balance, and convulsions. In some cases, listeriosis can be fatal, especially among the elderly, people with weakened immune systems, or chronic diseases.

To prevent listeriosis, it is recommended that people at high risk of infection avoid certain foods, including unpasteurized or raw milk, cheeses made from unpasteurized milk, raw fish, raw sprouts, and some other raw foods that carry a high risk of L. monocytogenes contamination. It is also important to follow food safety guidelines, such as keeping things clean, scrubbing raw vegetables, and cooking food thoroughly.

Safe cheese during pregnancy

When it comes to cheese during pregnancy, it's important to take some precautions due to the risk of bacterial infections, such as listeria, which can cause serious health issues for both mother and baby. However, this doesn't mean you have to give up cheese entirely! Here's a guide to help you navigate which cheeses are generally considered safe and which ones to avoid during pregnancy:

Safe Cheeses During Pregnancy:

• Hard cheeses: All hard cheeses, whether made with pasteurized or unpasteurized milk, are typically safe. Examples include Cheddar, Gouda, Swiss, Parmesan, and curds.
• Pasteurized soft cheeses: Many soft cheeses are safe to eat during pregnancy as long as they are made with pasteurized milk. This includes cream cheese, goat cheese (without the rind), cottage cheese, ricotta, Saint-Paulin, Havarti, mozzarella, and cheese spreads.
• Cooked soft cheeses: Soft, mold-ripened, or blue-veined cheeses can be consumed if they are cooked thoroughly to kill any bacteria. Oven-baked Camembert or Brie, for example, are safe options when cooked until piping hot, not just melted.
• Aged raw milk cheeses: Raw milk cheeses aged for over 60 days, such as Emmi Kaltbach Gruyère, Appenzeller, Hoch Ybrig, or Pleasant Ridge Reserve, are considered safe as they are too dry to harbour bacteria.

Cheeses to Avoid During Pregnancy:

• Soft, mold-ripened cheeses: These cheeses have a high water content, which can breed listeria. Even if pasteurized, they are not recommended due to their lower acidity, which makes them more susceptible to bacterial growth. This includes soft goat cheese with the rind and soft blue-veined cheeses.
• Soft, unpasteurized cheeses: During pregnancy, it's best to avoid unpasteurized cheeses, especially those without labels or from sources not inspected by the USDA. This includes Mexican-style cheeses like queso fresco and queso blanco, which are commonly made from raw cheese.

It's important to note that proper heating and pasteurization processes can kill harmful bacteria, but they may also affect the nutritional content of the cheese. Always check labels, and if in doubt, consult a healthcare professional for personalized advice regarding cheese consumption during pregnancy.

Cheese to avoid during pregnancy

When you're pregnant, it's important to be cautious about the types of cheese you consume, as some may be contaminated with bacteria that can harm your baby. Here's a guide to the cheeses to avoid during pregnancy:

Unpasteurized Cheeses:

Pregnant women should generally avoid consuming unpasteurized or raw milk cheeses. This is because unpasteurized cheeses may harbour harmful bacteria such as E. coli or Listeria, which can cause foodborne illnesses. While most infections are mild, there is a risk of more severe complications such as blood infection or meningitis. The concern is that these infections may be passed on to the baby, potentially leading to miscarriage, premature birth, illness, or even infant death.

Cheeses made with unpasteurized milk are typically found in the deli or specialty aisles of grocery stores, local farm stands, or farmers' markets. Examples of potentially unsafe cheeses include:

• Soft cheeses (e.g., Chavignol goat cheese, Coulommiers, Chabichou Valençay)
• Bacteria-ripened cheeses
• Blue-veined cheeses (e.g., Danish Blue, Gorgonzola, Roquefort)
• Mould-ripened soft cheeses with a white coating on the outside (e.g., Brie, Camembert, Chèvre)
• Cream cheese (e.g., Philadelphia)
• Melted cheese

Semi-soft, Blue, and Moulded-rind Cheeses:

Even if prepared from pasteurized milk, semi-soft, blue, and moulded-rind cheeses should be avoided during pregnancy. This is because they contain more moisture and are less acidic than hard cheeses, creating a favourable environment for the growth of Listeria bacteria. Examples of these cheeses include:

• Camembert
• Brie
• Blue cheese

Heat-treated Cheeses:

Heat-treated cheeses are made by heating the milk to approximately 55°C (131°F) for about 15 seconds. While this process kills off potentially dangerous bacteria, it is important to note that heat-treated cheeses still fall into the category of unpasteurized cheeses. Therefore, they should be avoided by pregnant women unless cooked to a high temperature (74°C or above) to ensure food safety.

In summary, during pregnancy, it is recommended to avoid unpasteurized cheeses and certain types of pasteurized cheeses, such as semi-soft, blue, and moulded-rind varieties. Cooking these cheeses at high temperatures can make them safe to consume. Always check labels carefully and opt for pasteurized cheeses whenever possible to reduce the risk of foodborne illnesses that could potentially harm you and your baby.

Frequently asked questions