Which component is NOT one of the main constituents of milk?

The main constituents of milk include water, lactose, and casein. Water is the primary component, making up about 87% of milk's composition. Lactose is the natural sugar found in milk, while casein is a type of protein that constitutes about 80% of the protein content in milk.

Fiber, on the other hand, is not a component of milk. It is primarily found in plant-based foods and is essential for digestive health, but milk does not contain any significant amounts of fiber. Therefore, identifying fiber as not being a main constituent of milk highlights an understanding of the nutritional composition of dairy products. Recognizing the key components of milk is important for discussions around nutrition, dietary needs, and food science.