Question

The enzymatic phase of rennet action is:

• A. Temperature independent
• B. Temperature dependent
• C. \(Ca^{2+}\) dependent
• D. \(Ca^{2+}\) independent

Hint:

Remember:
- Enzymatic phase = \(Ca^{2+}\) independent, relatively temperature-independent.
- Aggregation phase = \(Ca^{2+}\) dependent, highly temperature-dependent.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Rennet coagulation of milk occurs in two distinct, successive phases: a primary enzymatic phase and a secondary non-enzymatic coagulation phase.

Step 3: Detailed Explanation:
1. Primary (Enzymatic) Phase: The enzyme chymosin (rennet) specifically cleaves the peptide bond between Phenylalanine-105 and Methionine-106 of \(\kappa\)-casein. This cleavage releases hydrophilic glycomacropeptides into the whey, leaving hydrophobic para-\(\kappa\)-casein on the micelles. This enzymatic cleavage does not require calcium ions and is therefore \(Ca^{2+}\) independent.
2. Secondary (Non-enzymatic) Phase: The destabilized casein micelles aggregate to form a curd. This physical gelation process is highly dependent on temperature and requires calcium ions (\(Ca^{2+}\)) to form salt bridges between paracasein micelles.
Thus, the enzymatic phase is \(Ca^{2+}\) independent.

Step 4: Final Answer
The correct option is (D).