Question

Arrange the following milk products in descending order of "heat induced changes" during their preparation.
(A) Paneer
(B) Khoa
(C) Chakka
(D) Acid casein

• A. (A), (B), (C), (D).
• B. (C), (A), (B), (D).
• C. (B), (C), (A), (D).
• D. (B), (A), (C), (D).

Hint:

To arrange products by heat damage, identify the extreme ends:
- Khoa involves continuous open-pan concentration (highest heat).
- Acid casein requires low heat to prevent whey proteins from associating with the casein precipitate (lowest heat).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Heat-induced changes in dairy processing include the denaturation of whey proteins, complex formation between \(\beta\)-lactoglobulin and \(\kappa\)-casein, the Maillard browning reaction, and the conversion of soluble minerals into colloidal forms.
The extent of these changes depends on the temperature and duration of the thermal processing applied during product manufacture.

Step 2: Detailed Explanation:
Let us evaluate the thermal intensity used in the manufacturing process for each product:
1. Khoa (B): This product experiences the most intense thermal processing.
Milk is subjected to continuous boiling and evaporation in an open pan for several hours.
This prolonged heat treatment results in extensive Maillard browning, caramelization, complete whey protein denaturation, and mineral crystallization, representing the highest level of heat-induced changes.
2. Paneer (A): The milk is heated to \(82\text{--}90^\circ\text{C}\) and held for up to \(5\) minutes before acid coagulation.
This high heat treatment causes significant denaturation of whey proteins and their co-precipitation with casein, but is much less severe than the prolonged boiling used for Khoa.
3. Chakka (C): This is the concentrated curd intermediate used to make Shrikhand.
The milk is pasteurized under standard conditions (\(63^\circ\text{C}\) for \(30\text{ min}\) or \(72^\circ\text{C}\) for \(15\text{ s}\)) prior to fermentation and draining.
The heat-induced changes are minimal, primarily limited to standard pasteurization effects.
4. Acid casein (D): During the manufacture of industrial acid casein, skim milk is subjected to minimal pasteurization heat treatment (typically \(72^\circ\text{C}\) for \(15\text{ s}\)) and precipitated at warm temperatures (\(40\text{--}45^\circ\text{C}\)).
Preheating is minimized to prevent whey proteins from denaturing and associating with the casein, which would lower the purity of the isolated casein.

Step 3: Final Answer:
Arranging the products in descending order of heat-induced changes yields: Khoa (B) \(\rightarrow\) Paneer (A) \(\rightarrow\) Chakka (C) \(\rightarrow\) Acid casein (D).