Milk does not have a specific chemical or molecular formula; it is a variable mixture of water, fats, proteins and carbohydrates. Because the components of milk vary depending on fat and protein content, there is no single formula.
Cow milk is approximately 87 percent water. The other components of milk appear in varying content. For example, there is between 30 to 35 grams of protein per liter of normal milk. Casein by weight is between 76 percent to 86 percent of the molecules that comprise milk proteins.
The other components of milk, such as ions, colloids and emulsions, appear in different distributions. The distribution and concentration of components depend on environmental and herd management factors as well as multiple individual factors such as:
- Breed of the cow
- Stage of lactation