Question

The principal proteinase present in rennets is:

• A. Pepsin,
• B. Chymosin,
• C. Trypsin,
• D. Lipase.

Hint:

Chymosin is the enzyme that cleaves \(\kappa\)-casein, destabilizing the micelle to clot milk. Its high specificity for this single peptide bond makes it the ideal enzyme for cheese-making.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Rennet is a complex of gastric enzymes produced in the abomasum of young ruminants, used in cheese-making to coagulate milk.

Step 2: Detailed Explanation:
- The active ingredient and principal proteinase enzyme in animal rennet is Chymosin (also known as rennin).
- Chymosin is an aspartic endopeptidase that specifically cleaves the peptide bond between phenylalanine (at position 105) and methionine (at position 106) in the polypeptide chain of \(\kappa\)-casein.
- This cleavage removes the hydrophilic glycomacropeptide tail from the casein micelle, causing the destabilized micelles to aggregate and form a curd.
- While pepsin is also present in small quantities in adult animal rennets, chymosin is the primary enzyme responsible for the high-specificity clotting of milk in young calves.

Step 3: Final Answer
The principal proteinase in rennet is chymosin.