Fresh milk is slightly acidic. While its pH is close to 7 (neutral), the presence of lactic acid makes it slightly acidic, not truly neutral. The exact acidity varies based on factors like freshness and the source of the milk.
Understanding Milk Acidity
- pH Level: The pH of milk typically ranges from 6.7 to 6.9, placing it slightly below neutral. A pH of 7 is considered neutral. Anything below 7 is acidic; anything above 7 is alkaline (or basic).
- Lactic Acid: The primary contributor to milk's acidity is lactic acid, produced by naturally occurring lactobacillus bacteria. The amount of lactic acid increases as milk ages, leading to a more pronounced acidic taste and potentially souring.
- Types of Milk: The acidity can vary slightly depending on the type of milk (cow's milk, goat's milk, etc.) and processing (raw, pasteurized). Raw milk, for example, may have a different acidity level than pasteurized milk due to variations in bacterial activity.
The Role of Acidity in Milk
The slight acidity of milk plays a role in:
- Preservation: The acidity acts as a natural preservative, inhibiting the growth of certain harmful bacteria.
- Taste and Flavor: The lactic acid contributes to the characteristic taste of milk. As it increases, the milk becomes more sour.
- Dairy Processing: Acidity is an important factor in many dairy processing steps such as cheesemaking.
Several sources confirm the slightly acidic nature of milk:
- TutorOcean: States that fresh milk is slightly acidic but not a strong acid, with acidity varying depending on freshness and source. https://corp.tutorocean.com/chemistry/is-milk-an-acid-or-base/
- Healthline: Notes that fresh cow's milk is slightly acidic, with a pH of 6.7 to 6.9. https://www.healthline.com/health/ph-of-milk
- ScienceDirect: Highlights that the real acidity of milk is due to lactic acid. https://www.sciencedirect.com/science/article/pii/S0022030220942674/pdf?md5=9eec3ad72be2b5d7bf8eed47d2fee2a7&pid=1-s2.0-S0022030220942674-main.pdf
- LiveStrong: Confirms that milk's pH is 6.7 to 6.9, making it slightly acid-forming. https://www.livestrong.com/article/484688-milk-alkaline-acid/
