Which protein is main constituent of milk ?

Options

A. Casein
B. Insulin
C. Myosine
D. Keratin

Explanation

To determine the main protein constituent of milk, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options: chazine, insulin, myosin, and keratin.

2. **Understand the Role of Each Protein**:
- **Chazine**: This is a group name for the dominant class of proteins found in milk.
- **Insulin**: A hormone that regulates glucose levels in the blood, not a major protein in milk.
- **Myosin**: A protein primarily found in muscle tissues, not in milk.
- **Keratin**: A structural protein found in hair, nails, and skin, not in milk.

3. **Research the Composition of Milk**:
- Milk typically contains about 3.5% protein.
- Chazine constitutes about 80% of the total protein content in milk.

4. **Separation of Chazine**:
- Chazine can be separated from milk through methods like acid precipitation or adding rennet, which is commonly used in cheese-making.

5. **Conclusion**: Based on the information gathered, the main protein constituent of milk is **chazine**.

### Final Answer:
The main protein constituent of milk is **chazine**.

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