Question

Cow milk, an example of natural emulsion, is stabilized by
A. Fat
B. Water
C. Casein
D. $M{{g}^{2+}}$ ions

Answer 1

Cow milk is considered one of the most nutritious foods. It is the primary source of nutrition for the calf. Cow milk is majorly composed of water. It consists of dissolved solids that make up $10-14$. Fats, proteins, and lactose also make a small portion of the milk composition. The aqueous environment of milk makes up an emulsion and is stabilized by a protein.

Complete answer: Cow milk is a rich source of nutrition and makes the major dairy product to be used by humans. Milk is regarded as the whole food as it contains almost all the required nutrients. Casein makes up the largest protein portion of dissolved solids in the milk. It makes up 80% of the total proteins present in cow milk. The casein molecules form micelles. These are aggregates of several thousand protein molecules that resemble a surfactant micelle. The casein undergoes micelle formation along with calcium phosphate. Thus, most of the casein is in bound form in cow milk. 87% of the milk’s composition is water. This makes an aqueous environment around the total solids of milk. The micelles help in keeping the colloidal suspension of milk stable in this aqueous surrounding. This makes milk a natural emulsion. Other essential components of cow milk are fats 2.5-6%, lactose 3.6-5%, and proteins 2.5-9%. Other components like glucose, galactose, etc are present in minute quantities. Lactose is the main carbohydrate of milk that gives it its characteristic sweet taste.
Hence, the right answer is option C.

Note: The amount of casein is comparatively low in human milk as compared to cow milk. It is present between 20-45%. Casein is also used individually as a food additive. Casein also forms a major component of cheese. Casein supplies carbohydrates, amino acids, calcium, and phosphorus.