The Science Behind Cheese Acidity
The perception that all cheeses are acidic stems from the cheesemaking process, which begins with the acidification of milk. Cheesemakers add a starter culture of bacteria to milk, which then ferments the milk's lactose into lactic acid. This lactic acid production causes the milk's pH to drop, leading to the coagulation of casein proteins and the formation of curds. The degree and duration of this initial acidification are the first and most fundamental steps in determining the final pH of the cheese.
Beyond this initial step, cheesemakers can manipulate the cheese's pH through various techniques. For instance, the curd can be washed to remove residual lactose, which limits the amount of lactic acid the bacteria can produce, resulting in a less acidic final product. The temperature during cheesemaking and the length of aging also play a significant role. Over time, particularly in mold-ripened and washed-rind cheeses, the pH can actually increase as microorganisms break down proteins into more alkaline compounds like ammonia.
How Cheese pH Affects Flavor and Texture
The pH level is not just a scientific measurement; it is a primary determinant of a cheese's sensory characteristics. The relationship between pH, flavor, and texture is a cornerstone of cheesemaking artistry.
- Acidity and Flavor: Cheeses with a lower pH (more acidic) often have a sharper, tangier flavor profile. The high concentration of lactic acid is responsible for this characteristic bite found in many cheddars. As a cheese's pH rises, its flavor typically becomes milder and more buttery, or in the case of surface-ripened cheeses, more pungent and complex due to the action of different microbes.
- Acidity and Texture: The pH affects the way calcium is bound within the cheese's protein matrix. In more acidic cheeses (low pH), calcium is more easily released from the curd, leading to a firmer, more crumbly texture. Cheeses with a higher pH (less acidic) retain more calcium, resulting in a softer, more elastic body. This is why a fresh mozzarella, with a moderate pH, is stretchy, while a high-acid feta is crumbly.
Different Cheeses, Different pH Levels
To understand why the blanket statement "all cheese is acidic" is incorrect, one must look at the diverse range of cheese types and their final pH values. The scale below illustrates the spectrum, from highly acidic to near-neutral.
Common Cheeses and their Typical pH Ranges:
- Highly Acidic (pH < 5.0):
- Cottage Cheese: 4.5–5.0
- Feta: 4.6–4.9
- Cream Cheese: 4.4–4.9
- Moderately Acidic (pH 5.0–6.0):
- Cheddar: 5.1–5.4
- Parmesan: 5.2–5.4
- Swiss: 5.6–5.8
- Ricotta: 5.7–6.3
- Processed American Cheese: 5.5–6.0
- Near-Neutral/Alkaline (pH > 6.0):
- Blue Cheeses (e.g., Roquefort, Gorgonzola): 6.0–7.0
- Soft-Ripened Cheeses (e.g., Brie, Camembert): 6.0–7.0
- Washed-Rind Cheeses (e.g., Limburger): >6.2
Cheese pH vs. Dietary Acid-Forming Potential
While the cheese's actual pH is important for its intrinsic properties, nutrition science also considers a food's potential renal acid load (PRAL). The PRAL value measures a food's acid or alkaline-forming potential after it has been metabolized by the body. Dairy products, including cheese, are generally considered acid-forming in metabolic terms, not because of their pH alone, but because of their high protein and phosphorus content relative to their mineral content. However, the body's pH is tightly regulated and not significantly altered by diet for healthy individuals.
For those with specific health conditions, such as acid reflux or GERD, the direct acidity of the food can matter. High-fat foods like cheese can slow digestion, putting pressure on the lower esophageal sphincter and potentially causing or worsening acid reflux symptoms. Therefore, for these individuals, a lower-fat, less acidic cheese option might be preferable.
Comparison Table: Acidic vs. Less Acidic Cheeses
| Feature | Acidic Cheeses (e.g., Feta, Young Cheddar) | Less Acidic Cheeses (e.g., Blue Cheese, Brie) |
|---|---|---|
| Typical pH Range | Lower (e.g., 4.5–5.4) | Higher, often above 6.0 |
| Primary Acid | Lactic acid from bacterial fermentation | Less lactic acid; proteins broken down into more alkaline compounds |
| Flavor Profile | Sharp, tangy, pronounced bite | Milder, buttery, or pungent and complex |
| Texture | Firmer, more crumbly, often brittle | Softer, more elastic, and sometimes gooey |
| Aging | Often aged to develop sharpness; pH can increase slowly | Ripens to a higher pH, often becoming less acidic over time |
Conclusion: The Final Verdict on Cheese Acidity
To definitively answer the question "Are all cheeses acidic?", the answer is no. Cheese is not a monolithic product; its pH is a variable that is influenced by a multitude of factors during its creation and aging, most notably bacterial cultures and specific techniques like curd washing. While the journey from milk to cheese inevitably involves an initial acidification process, the final product's pH can span a wide range. Cheeses like feta and cheddar remain highly acidic, contributing to their characteristic firm texture and sharp flavor. In contrast, soft-ripened and blue cheeses can develop a near-neutral or even slightly alkaline pH as they mature, leading to their distinctively milder or more pungent characteristics.
For most people, the overall dietary context and nutrient density are more significant for health than a cheese's specific pH or metabolic acid-forming potential. However, understanding these variations is invaluable for individuals managing specific health concerns like acid reflux or for discerning cheese lovers who want to appreciate the nuances of their favorite dairy products. A balanced nutritional diet embraces the full spectrum of cheese, recognizing its diversity in composition, flavor, and effect on the body.
Visit the Center for Dairy Research for more information on the science of cheese.
