Lactic acid is the primary acid found in milk. While other acids exist in smaller quantities, lactic acid is the dominant one, especially as milk sours.
What is Lactic Acid?
Lactic acid is a weak acid naturally produced by bacteria during the fermentation process of lactose (milk sugar). This process, called lactic acid fermentation, is responsible for the souring of milk.
- Sour Milk: The increase in lactic acid is what gives sour milk its characteristic tart taste.
- Role in the Body: Lactic acid also plays a role in the human body as a byproduct of muscle metabolism.
- Calcium Salt: The calcium salt of lactic acid is a crucial source of calcium for growing animals.
Other Acids Present in Milk
While lactic acid is the predominant acid, other acids are present in smaller amounts:
- Fatty Acids: Milk contains various fatty acids, such as trans-vaccenic acid (TVA) and arachidonic acid (ARA). These are components of milk fat and contribute to overall nutritional value.
- Sialic Acid: Present in human milk, sialic acid contributes to the overall composition and health benefits of breast milk. It's especially prevalent in bound oligosaccharides.
Apparent vs. Real Acidity in Milk
Dairy scientists differentiate between apparent acidity (total acidity) and real acidity (lactic acid). Real acidity, however, primarily refers to the concentration of lactic acid.
The Importance of Lactic Acid in Milk Analysis
The titratable acidity of milk, a measure of its total acidity, is often expressed in terms of lactic acid due to its significant presence.
