Understanding Pasteurization vs. Raw Milk
Pasteurization is the process of heating milk to a specific temperature for a set period to kill potentially harmful bacteria, such as Listeria, Salmonella, and E. coli. Raw milk, by contrast, is not heated to these high temperatures, retaining its natural bacterial flora and enzymes. This retention is what some connoisseurs believe contributes to a more complex and robust flavor profile in the final cheese.
The FDA's 60-Day Aging Rule
In the United States, cheese made from unpasteurized milk is not required to be pasteurized if it is aged for at least 60 days at a minimum of 35°F. This regulation applies to both domestic and imported raw milk cheeses. The rationale behind this rule is that the aging process, combined with other factors inherent in hard cheesemaking, creates an inhospitable environment for pathogens.
How aging makes cheese safer
The safety of aged hard cheeses relies on a combination of factors, often referred to as the "hurdle effect".
- Low moisture content: Hard cheeses naturally have low moisture, which is a key requirement for bacterial growth. Pathogens find it difficult to multiply without sufficient water.
- High salt content: The salt added during the cheesemaking process also inhibits the growth of harmful bacteria.
- High acidity: The increased acidity from the fermentation process further suppresses unwanted microbial activity.
Flavor and Texture: Unpasteurized vs. Pasteurized Hard Cheese
The choice between pasteurized and unpasteurized hard cheese often comes down to taste preference. Artisans who use raw milk argue it allows the terroir—the local environment, including the feed of the animals and the climate—to shine through, creating a distinctive and nuanced flavor. Pasteurized cheese, while still delicious, can offer a more consistent and predictable flavor profile, which is important for large-scale production.
Identifying Unpasteurized Hard Cheeses
For those concerned about or seeking out unpasteurized cheese, the label is your most important tool. By law, cheese made with raw milk must be clearly labeled.
To identify an unpasteurized hard cheese:
- Look for phrases like "raw milk," "unpasteurized," or the French equivalent, "au lait cru".
- At a cheese counter where products are unpackaged, ask the cheesemonger directly if the cheese is made with raw milk.
- In some cases, specific regional designations, like Parmigiano-Reggiano, legally mandate the use of unpasteurized milk.
Health Considerations
While aged raw milk hard cheeses are generally safe for the majority of the population, certain groups are advised to be cautious.
- Vulnerable populations: Pregnant women, young children, the elderly, and individuals with weakened immune systems are typically advised by health authorities to avoid unpasteurized cheeses.
- Cooking as a safety measure: For those who wish to consume raw milk cheese but are concerned about potential risks, cooking the cheese until it is steaming hot will kill any harmful bacteria.
Comparing Unpasteurized and Pasteurized Hard Cheeses
| Feature | Unpasteurized Hard Cheese | Pasteurized Hard Cheese |
|---|---|---|
| Milk Treatment | Mildly heated (below pasteurization temp) to preserve enzymes and beneficial bacteria. | Heated to a specific temperature for a set time to kill pathogens. |
| Flavor Profile | Known for more complex, robust, and nuanced flavors influenced by 'terroir'. | Consistent, predictable, and often milder flavor. |
| Safety (Aged >60 days) | Considered safe for most consumers due to low moisture, high acidity, and aging process. | Considered very low risk due to heat treatment of the milk. |
| Labeling | Legally required to state "raw milk" or "unpasteurized" on the label. | Typically not labeled as "pasteurized" as it's the standard for most mass-produced cheeses. |
| Examples | Some artisanal Cheddar, Parmigiano-Reggiano, Comté. | Most mainstream Cheddar, Swiss, and Gouda. |
Conclusion
The notion that all hard cheeses are unpasteurized is a myth. The reality is more nuanced, with both pasteurized and unpasteurized options widely available. The key difference lies in the initial milk treatment, which influences the final cheese's flavor and texture. For hard raw milk cheeses sold in the U.S., a strict 60-day aging period, along with naturally low moisture and high acidity, ensures a product that is safe for most people to consume. By reading labels and understanding these distinctions, consumers can make informed choices based on both their flavor preferences and health considerations.
Learn more about cheese aging and safety guidelines from the Centers for Disease Control and Prevention.
