What happens to milk if it boils?

1. Protein Denaturation: The high temperature during boiling causes the proteins in milk to denature. Denaturation is the process by which the protein structure unfolds, leading to changes in its physical and functional properties. This is why boiled milk appears thicker or clotted.

2. Maillard Reaction: Boiling milk can initiate the Maillard reaction, which is a chemical reaction between amino acids and sugars. This reaction is responsible for the browning color and the development of a characteristic flavor in boiled milk.

3. Lactose Caramelization: Lactose, the natural sugar present in milk, can undergo caramelization when exposed to high heat. Caramelization involves the browning and development of a slightly sweet flavor in the milk.

4. Loss of Nutrients: Prolonged boiling can cause the loss of some heat-sensitive nutrients present in milk, including vitamins, such as vitamin C and B vitamins. Minerals, such as calcium, are generally not significantly affected.

5. Bacterial Elimination: Boiling milk effectively destroys harmful bacteria, making it safe for consumption. This process is essential in regions where there are concerns about milk contamination.

It's important to note that boiling milk for an extended period can alter its taste and texture and cause it to develop a "cooked" flavor. To preserve the flavor, nutritional content, and texture of milk, it's generally recommended to heat milk to a temperature just below boiling (approximately 175°F or 80°C) and then remove it from the heat source.