Answer:

Introduction:
Emulsifiers are substances that help stabilize emulsions, which are mixtures of two immiscible liquids, such as oil and water. Emulsifiers have an important role in the food industry, especially in the production and stabilization of various emulsion-based products. One such emulsion is milk, which is a mixture of fat globules dispersed in water.

Explanation:
The emulsifier that stabilizes the milk emulsion is casein. Casein is a protein found in milk and is responsible for the white color of milk. It acts as a natural emulsifier and helps to stabilize the milk emulsion by preventing the separation of fat globules from the water phase.

Role of Casein:
1. Emulsification: Casein molecules have hydrophilic (water-loving) and hydrophobic (fat-loving) regions. The hydrophilic regions interact with water molecules, while the hydrophobic regions interact with fat globules. This allows casein to form a protective layer around fat globules, preventing them from coalescing and separating from the water phase.

2. Stabilization: The protective layer formed by casein around fat globules stabilizes the milk emulsion by reducing the surface tension between fat and water. This prevents the fat globules from clustering together and floating to the surface as cream.

3. Prevention of Coalescence: Casein also prevents the coalescence or merging of fat globules by forming a physical barrier between them. This helps to maintain the uniform distribution of fat globules throughout the milk.

Other Emulsifiers in Milk:
While casein is the primary emulsifier in milk, there are other minor emulsifiers present as well. These include phospholipids and other proteins like whey proteins. However, casein is the main emulsifier responsible for stabilizing the milk emulsion.

Conclusion:
In conclusion, the emulsifier that stabilizes milk emulsion is casein. Casein, a protein found in milk, forms a protective layer around fat globules, preventing them from coalescing and separating from the water phase. This stabilizes the milk emulsion and helps to maintain its homogeneous texture.