Question

Given below are two statements related to paneer manufacture:
Statement (I) : The coagulum formation in paneer involves progressive removal of tricalcium phosphate from the surface of the casein after acidification.
Statement (II) : Dispersion of casein is not stable which gets precipitated to form coagulum embedding fat into it.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Acid coagulation of milk (as in Paneer or Chhana) occurs because:
1. Acid dissolves the stabilizing colloidal calcium phosphate from casein micelles.
2. Caseins reach their isoelectric point (\(\text{pH } 4.6\)), lose their charge, and precipitate, trapping fat globules.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Paneer is a traditional South Asian acid-coagulated dairy product.
Its manufacture relies on heat-induced whey protein denaturation followed by organic acid precipitation at high temperatures.

Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement (I) is correct: In raw milk, casein micelles are stabilized by steric and electrostatic repulsion.
This stability is maintained by colloidal calcium phosphate (CCP), primarily in the form of tricalcium phosphate, which is distributed throughout the micelle structure.
During paneer manufacture, hot milk (\(80\text{--}90^\circ\text{C}\)) is acidified by adding citric or lactic acid.
This acidification lowers the pH, converting the insoluble colloidal calcium phosphate into soluble calcium ions that dissolve into the surrounding serum.
This progressive loss of calcium phosphate destabilizes the micellar structure.
- Statement (II) is correct: As the pH approaches the isoelectric point of casein (\(\text{pH } 4.6\)), the negative electrical charge on the micelles is neutralized.
Because the electrostatic repulsion is minimized, the colloidal dispersion of casein becomes unstable.
The destabilized casein molecules aggregate and precipitate out of solution, forming a three-dimensional protein network (coagulum).
As this network forms, it physically traps and embeds suspended fat globules and some whey within its structure, yielding the characteristic soft, cohesive texture of paneer.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.