Heating Unpasteurized Cheese: How Long Is Safe?

Unpasteurized cheese, also known as raw-milk cheese, is made from milk that has not been heated to a high enough temperature to kill harmful bacteria. While some may be hesitant to try it due to safety concerns, many believe that its benefits and flavour make it worth exploring. In this article, we will be discussing how long unpasteurized cheese should be heated.

How long to heat unpasteurized cheese to make it safe

Unpasteurized cheese, also known as raw-milk cheese, is made from milk that has not been pasteurized. Pasteurization is the process of heating milk to a high temperature to destroy microorganisms that can cause sickness or spoilage. The exact temperature and duration of heating depend on the specific pasteurization method used.

In the United States, unpasteurized cheese cannot be sold unless it has been aged for at least 60 days. This aging period is believed to naturally prevent harmful bacteria such as Listeria, Salmonella, and E. coli from growing. The aging process, along with the acids and salts in the cheese, are thought to be sufficient to make the cheese safe for consumption. Therefore, the heating process to make unpasteurized cheese safe is not dependent on a specific temperature or duration, but rather on the length of the aging period.

However, it is important to note that the risk of foodborne illnesses from consuming unpasteurized cheese is still present, as evidenced by recent bacterial outbreaks linked to raw-milk cheese. While the aging process reduces this risk, it does not entirely eliminate it.

In contrast, pasteurized cheese is made by heating milk to approximately 65° C (149° F) to kill pathogenic bacteria. This process ensures the safety of the cheese but may also impact its flavor by killing some of the good bacteria that contribute to its unique, complex flavors.

In summary, to make unpasteurized cheese safe, it should be aged for at least 60 days, rather than heated to a specific temperature for a set duration. However, it is important to be aware of the potential risks associated with consuming unpasteurized cheese, especially for certain vulnerable groups such as pregnant women, the elderly, or those with compromised immune systems.

Pasteurization temperatures and times

Pasteurization is a process that involves applying heat to destroy pathogens in foods. It is named after the French scientist Louis Pasteur, who discovered that heating wine and beer to about 57 °C (135 °F) for a few minutes could prevent abnormal fermentation.

The temperatures and times for pasteurization depend on the specific type of milk or milk product being treated, as well as the equipment used and the region's regulations. Here are some common pasteurization methods and their associated temperatures and times:

• High-Temperature Short-Time (HTST) Pasteurization: This is the most common method in the United States. It involves heating milk to at least 161 °F (71.7 °C) for not less than 15 seconds, followed by rapid cooling.
• Low-Temperature Long-Time (LTLT) Pasteurization: This method is often used in small-scale and artisanal cheesemaking operations. Milk is heated to 63 °C (145 °F) for 30 minutes.
• Higher Heat Shorter Time (HHST) Pasteurization: This method is similar to HTST but uses slightly different equipment and higher temperatures for a shorter time.
• Ultra-High Temperature (UHT) Pasteurization: This process involves heating milk or cream to 138–150 °C (280–302 °F) for one or two seconds. UHT milk is packaged in sterile, hermetically sealed containers and can be stored without refrigeration for months.
• Ultra Pasteurization (UP): For a product to be considered Ultra Pasteurized, it must be heated to 280 °F (137.8 °C) for two seconds. UP products have a longer shelf life but still require refrigeration.
• Heat-Treated Milk: This method is considered a good balance between pasteurized and unpasteurized milk. Milk is heated to approximately 55 °C (131 °F) for about 15 seconds, which is enough to kill off dangerous bacteria while preserving most of the complex flavours.

It is important to note that the exact temperatures and times may vary slightly depending on the specific regulations and equipment used. Additionally, these methods are primarily focused on milk pasteurization, and the temperatures and times may differ for other types of foods.

Risks of eating unpasteurized cheese

Unpasteurized cheese, also known as raw-milk cheese, is made from milk that has not been heated to a high enough temperature to kill potentially harmful bacteria. These bacteria can cause serious illness, especially in people with weakened immune systems, children, older adults, and pregnant women.

According to the US Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), and other US agencies, raw milk is especially unsafe for infants and young children, the elderly, and the immunocompromised. The CDC also highlights that foodborne illness from raw milk disproportionately affects children and teenagers.

Pregnant women are at a heightened risk of becoming ill from the Listeria bacteria, which is often found in raw milk and can cause miscarriage, or illness or death of the newborn baby. If you are pregnant, it is best to avoid unpasteurized cheese or milk products.

Symptoms of foodborne illness from raw milk can include vomiting, diarrhea, abdominal pain, and flu-like symptoms such as fever, headache, and body aches. While most healthy people will recover from an illness caused by harmful germs in raw milk or raw-milk products within a short time, some can develop chronic, severe, or even life-threatening symptoms.

In the United States, unpasteurized cheese can be sold, but it must be aged for at least 60 days before retailers are allowed to sell it. This is because dangerous bacteria, like listeria, cannot survive past this period, so it is believed that the lengthened aging process removes the dangers of eating unpasteurized cheese.

Outside the US, unpasteurized cheese is much more common and less regulated. When travelling abroad, it is more likely that you will encounter unpasteurized cheeses, as the dairy industries outside the US are much less regulated.

Why is pasteurized cheese considered safer?

Pasteurized cheese is considered safer than unpasteurized cheese because of the pasteurization process, which involves heating milk to a high temperature to kill potentially harmful bacteria. Unpasteurized cheese, also known as raw-milk cheese, is made from milk that has not undergone this process and therefore may contain bacteria that can cause foodborne illnesses.

The pasteurization process was discovered by French scientist Louis Pasteur in 1862. To pasteurize milk, it is heated to a temperature of 161 °F (71.7 °C) for 15 seconds or to 145 °F (62.8 °C) for 30 minutes or more. This process kills pathogens such as Listeria, E. coli, Staphylococcus aureus, and Salmonella, which can be present in raw milk. In contrast, unpasteurized cheese is made by heating milk to only about 86 °F (30 °C), which is just enough for the milk to start fermenting and become cheese.

The safety of unpasteurized cheese has been a topic of debate among cheese enthusiasts and lawmakers. Proponents of raw-milk cheese argue that it has been made and consumed safely for centuries, especially in Europe, where many traditional cheeses are made with raw milk. They also argue that the enzymes in raw milk cheese are healthier and aid digestion. However, unpasteurized cheese is considered unsafe for certain vulnerable populations, including infants, young children, pregnant women, the elderly, and immunocompromised individuals.

To address the safety concerns, regulations have been put in place in various countries. For example, in the United States, the Food and Drug Administration (FDA) banned the interstate sale of raw milk in 1987, and unpasteurized cheese can only be sold if it has been aged for at least 60 days. This extended aging process is believed to naturally prevent the growth of harmful bacteria such as Listeria, Salmonella, and E. coli. Similarly, in Canada, unpasteurized cheese must be aged for at least 60 days before being sold to consumers.

In summary, pasteurized cheese is considered safer due to the destruction of harmful bacteria through the pasteurization process. However, it is important to note that pasteurization can also kill beneficial bacteria that contribute to the flavor and health benefits of cheese. The choice between pasteurized and unpasteurized cheese ultimately depends on various factors, including individual health considerations, taste preferences, and local regulations.

How to tell if a cheese is pasteurized

Pasteurization is the process of heat-treating milk to destroy potentially harmful pathogens, such as Salmonella. In Canada, unpasteurized cheese, or raw milk cheese, can be sold but must be aged for at least 60 days before retailers are allowed to sell it. By this time, it is considered safe as any potentially harmful bacteria will have died off naturally.

To make unpasteurized cheese, the milk is heated to about 30° C (86° F). This is just enough heat to allow the milk to start fermenting and become cheese. The bacterial compounds of the cheese are not destroyed, resulting in a much more flavourful, powerful cheese.

On the other hand, pasteurized cheese involves heating milk to approximately 65° C (149° F) to kill off any pathogenic bacteria. This process is considered more efficient on a large scale, requiring less care in the milk collection stage where bacteria from cows run rampant. It also extends the shelf life of dairy products. However, it kills the good bacteria that give some raw milk cheeses their unique, complex flavours.

So how can you tell if a cheese is pasteurized? Here are some ways to determine if a cheese has been pasteurized:

• Check the label: Look for cheese that is labeled "pasteurized". This indicates that the cheese has been heat-treated to destroy harmful bacteria.
• Type of cheese: In the US, nearly all fresh (unaged, rindless) cheeses, such as mozzarella, fresh goat cheese, ricotta, or feta, are pasteurized. Additionally, 99% of soft, creamy, spreadable cheeses like Laughing Cow, Brie, Camembert, or Taleggio are pasteurized. Harder, aged cheeses may or may not be pasteurized, and are available in both raw and pasteurized forms.
• Country of origin: Imported cheese is more likely to be unpasteurized than domestic cheese. European countries, for example, have a long tradition of consuming unpasteurized cheese.
• Moisture content: Soft cheeses have a higher moisture content, which provides a more hospitable environment for bacteria like Listeria. Harder, drier cheeses are less likely to harbour or grow such pathogens.
• Age of cheese: If a cheese is less than 60 days old, it must be made of pasteurized milk in the US. Cheeses older than 60 days may be made of pasteurized or unpasteurized milk, as the aging process is considered sufficient to kill any harmful bacteria.
• Place of purchase: Soft cheeses that are pre-packaged are more likely to be pasteurized, while those purchased from a deli counter may be at a higher risk of contamination.

It's important to note that even pasteurized cheese can become contaminated with Listeria or other pathogens during the supply chain, such as through contact with contaminated deli meat or other cheese. To minimize this risk, it's recommended to buy individual rounds of pasteurized cheese instead of cut pieces from a larger wheel.

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