The Cornerstone of Safety: Pasteurization vs. Raw Milk
For the vast majority of consumers, the single most important factor determining the safety of cheese is whether it was made from pasteurized or unpasteurized (raw) milk. Pasteurization is a heat-treatment process that kills harmful bacteria like Listeria, Salmonella, and E. coli that can be present in raw milk. The US Food and Drug Administration (FDA) and CDC strongly recommend that vulnerable populations—including pregnant women, the elderly, young children, and those with weakened immune systems—consume only pasteurized dairy products.
While some raw milk cheeses are aged for at least 60 days to reduce bacterial risk, recent studies have shown that pathogens can persist even in aged raw milk cheese. For example, a 2025 FDA-supported study on avian influenza (HPAI H5N1) found that infectious virus could survive the 60-day aging process in certain raw milk cheeses, highlighting ongoing public health risks. For the highest level of assurance, choosing pasteurized cheese is the most reliable strategy, especially for those in high-risk groups.
Hard vs. Soft Cheese: Understanding the Role of Moisture
Beyond pasteurization, the moisture content of cheese is a critical indicator of its safety. Harmful bacteria like Listeria monocytogenes thrive in moist, low-acidity environments.
Hard, Aged Cheeses
Hard, aged cheeses are considered the safest option for several reasons. Their low moisture content and higher acidity create an environment that is hostile to most harmful bacteria, making it difficult for pathogens to multiply. Examples of very safe hard cheeses include:
- Parmesan (Parmigiano Reggiano)
- Aged Cheddar
- Swiss (Emmental, Gruyère)
- Colby
Soft and Semi-Soft Cheeses
Soft and semi-soft cheeses, with their higher moisture content, provide a more hospitable environment for bacterial growth. This includes mould-ripened soft cheeses like Brie and Camembert, as well as soft Mexican-style cheeses like queso fresco and queso blanco. While pasteurization significantly reduces the risk, post-processing contamination can still occur. For this reason, vulnerable individuals are advised to avoid soft cheeses unless they have been cooked thoroughly to a steaming hot temperature.
Proper Handling and Storage for Maximum Safety
Even the safest cheese can become a health risk if not handled and stored correctly. Follow these guidelines to maintain cheese safety:
- Refrigerate Promptly: Always refrigerate cheese as soon as possible after purchase.
- Maintain Cold Temperatures: Store cheese in the refrigerator between 35°F and 40°F.
- Limit Time at Room Temperature: Do not leave moist cheeses, such as ricotta or mozzarella, out for more than two hours.
- Prevent Cross-Contamination: Use separate knives and cutting boards for different cheeses, or thoroughly clean them between uses.
- Rewrap Correctly: After opening, rewrap cheese tightly in fresh, moisture-proof wrap (like foil or parchment paper) to prevent drying and mold growth.
Dealing with Mold on Cheese
It is important to distinguish between molds that are intentionally part of the cheesemaking process and molds that appear from spoilage. Cheeses like blue cheese, Brie, and Camembert use specific, harmless molds for flavor and texture. However, unwanted mold growth should be addressed differently based on the cheese type.
- Hard Cheeses: For hard, dense cheeses like Parmesan or Cheddar, mold cannot penetrate deeply. You can cut off at least one inch around and below the mold spot, keeping the knife clean to avoid cross-contamination. The remaining cheese is safe to eat.
- Soft Cheeses: Any visible mold on soft cheeses (including fresh cheeses like cottage cheese and ricotta) means the entire product should be discarded. The high moisture content allows mold to spread quickly throughout, even if not visible on the surface.
Cheese Safety Comparison Table
| Cheese Type | Pasteurization | Moisture Level | Safety for High-Risk Groups | General Safety | Special Considerations |
|---|---|---|---|---|---|
| Hard Cheese (e.g., Parmesan, Aged Cheddar) | Often Unpasteurized (but aged > 60 days) or Pasteurized | Low | Generally Safe | Very Safe | Aging process reduces bacteria; always trim surface mold. |
| Soft Cheese (e.g., Brie, Camembert) | Can be Pasteurized or Unpasteurized | High | Avoid (unless cooked until steaming hot) | Caution Advised | Risk of Listeria contamination, even if pasteurized. Cooking required for safety. |
| Fresh Cheese (e.g., Ricotta, Cottage) | Usually Pasteurized | Very High | Can be Safe (if pasteurized) | High Safety (if pasteurized) | Check label for pasteurization; discard if any mold appears. |
| Pasteurized Processed Cheese | Pasteurized | Low to Moderate | Safe | Very Safe | Processed to kill all bacteria; highly stable. |
Conclusion: Prioritizing Informed Choices
For the most reliable safety, the best cheese to eat is one made from pasteurized milk, particularly hard and aged varieties. These options have significantly lower risks of harboring foodborne pathogens like Listeria. While many individuals enjoy raw milk or soft cheeses without issue, understanding the heightened risks for vulnerable populations is crucial. For those who are pregnant, elderly, or immunocompromised, strict adherence to pasteurized, hard cheeses, or thoroughly cooking other varieties, is the wisest choice. Always prioritize proper storage and handling to enjoy your cheese safely.
For more information on cheese safety, refer to the CDC Food Safety Guidelines.
Guidance for High-Risk Individuals
Individuals with weakened immune systems or those who are pregnant or elderly need to take extra precautions with cheese consumption. These groups are at a much higher risk of developing serious complications from bacterial infections like listeriosis. Beyond simply choosing pasteurized products, it is vital to avoid soft cheeses, mould-ripened cheeses, and Mexican-style cheeses unless they are cooked until steaming hot. The CDC and other health agencies have repeatedly stressed these recommendations to prevent severe illness.
Making Safe Cheese at Home
For home cheesemakers, ensuring safety is paramount. The process of cheesemaking involves careful sanitation and temperature control to prevent the growth of harmful bacteria. Always start with pasteurized milk unless you are an experienced cheesemaker and are prepared to manage the risks associated with raw milk. Every piece of equipment, from curd knives to molds, must be thoroughly cleaned and sanitized before use. Proper hygiene is essential throughout the entire process, including clean clothing and hands. Inadequate sanitization can introduce unwanted microbes that compromise the safety and flavor of the final product.
The Flavor vs. Safety Debate
For cheese aficionados, the debate over pasteurized versus raw milk cheese often comes down to flavor complexity. Advocates for raw milk cheese argue that it offers more nuanced and diverse flavors, which are sometimes diminished by the heating process of pasteurization. However, modern cheesemakers are increasingly able to produce delicious, complex cheeses from pasteurized milk by carefully managing starter cultures and aging conditions. While the perceived flavor differences are a matter of personal preference, the scientific evidence on safety points clearly towards pasteurized products for the lowest risk of foodborne illness.
A Final Word on Serving Cheese Safely
When serving cheese, particularly at a party or gathering, consider the ambient temperature. Soft, high-moisture cheeses should not be left out for extended periods, especially in warmer conditions. It is better to bring out smaller quantities at a time and replenish as needed to ensure safety. For a large platter, focus on harder, aged cheeses that are more resilient to temperature changes, and provide specific information for guests who may be in high-risk categories.
Ultimately, making the safest choice depends on individual risk tolerance and health status. However, a firm grasp of the facts concerning pasteurization, moisture, and proper handling ensures you can enjoy cheese confidently and responsibly.
