The pH of lactic acid in milk is a critical aspect of dairy products, particularly in the production of cheese. Understanding the pH range, its effects on cheese, and the role of lactic acid in milk is essential for cheesemakers and dairy enthusiasts alike.
Definition and Measurement of pH
pH is a measure of acidity, which is crucial in cheese making. It represents the number of free protons (H+ atoms) present in milk or cheese. The pH scale ranges from 0 to 14, with lower values indicating higher acidity and higher values indicating lower acidity.
pH Range of Milk and Cheese
Milk typically starts with a pH of around 6.7, which can vary depending on the type of cheese being produced. Different cheeses have distinct pH ranges:
| Cheese Type | pH Range |
|---|---|
| Limburger, Blue Cheese, Brie, Quesco Fresco, Bread Cheese | 6.5-6.2 |
| Ricotta, Brick | 6.0-5.8 |
| Gruyere, Swiss, Fresh Mozzarella | 5.7-5.5 |
| Gouda, Mozzarella, Parmesan, Colby, Cheddar | 5.4-5.1 |
| Cream Cheese, Feta, Cottage Cheese | 4.9-4.6 |
Effects of pH on Cheese
The pH of milk and cheese affects various aspects of the final product, including coagulation, flavor, melting properties, and safety. Lower pH (higher acidity) inhibits the growth of pathogens, making the cheese safer for consumption.
pH also influences the growth and activity of lactic acid bacteria, such as Streptococcus thermophilus (pH 6.5), Lactobacillus bulgaricus (pH 5.8-6), and Lactococcus lactis subsp. cremoris (pH 6.3-6.9). These bacteria play a crucial role in the fermentation and maturation of cheese.
Lactic Acid in Milk
Milk contains lactic acid, which is produced by bacteria converting lactose into lactic acid. This process lowers the pH of milk, making it more acidic. As milk becomes sour due to bacterial activity, the pH can decrease.
Contaminants and Chemicals
Contaminants in milk, such as bacteria, can affect the pH and overall quality of the milk. Chemicals like trichloroacetic acid and propionic acid are used in the analysis of lactic acid concentrations in milk.
Balancing pH and Home Remedies
To balance the pH of milk, cheesemakers can add acid or use starter cultures to control the acidity level. For home remedies, it is essential to maintain proper hygiene and handling practices to prevent contamination and ensure the desired pH range for the specific dairy product being produced.
Helpful pH Quantity to Consume
The ideal pH for consumption depends on the type of dairy product. For example, milk is typically consumed at a pH around 6.7, while cheese can have a wide range of pH values depending on the type.
History
The understanding of pH and its importance in dairy products has evolved over time, with the development of modern cheese-making techniques and the use of starter cultures to control acidity.
References
- Cheese Science Toolkit. (n.d.). pH. Retrieved from https://www.cheesescience.org/ph.html
- ThoughtCo. (2022, September 30). Do You Know If Milk Is an Acid or a Base? Retrieved from https://www.thoughtco.com/milk-an-acid-or-a-base-607361
- NCBI. (n.d.). Fermentation pH Influences the Physiological-State Dynamics of Lactobacillus bulgaricus CFL1. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704822/.