Question

Colostrum has low heat stability due to presence of high amounts of __________.

• A. Sodium
• B. Fat
• C. Protein
• D. Chloride

Hint:

The total protein content of first-milking colostrum is up to five times higher than mature milk, driven by immunoglobulins.
These whey proteins denature easily, causing immediate coagulation upon heating.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Colostrum is the initial milk secreted by female mammals immediately following parturition.
It has a significantly different chemical composition compared to normal, mature milk, which makes it highly sensitive to thermal processing.

Step 2: Detailed Explanation:
The heat stability of milk is primarily governed by the concentration and state of its proteins, particularly the ratio of heat-sensitive whey proteins to stable caseins.
Normal mature milk contains approximately \(3.2\%\) to \(3.5\%\) total protein, with whey proteins representing only about \(18\%\) to \(20\%\) of that fraction.
In contrast, colostrum contains an exceptionally high total protein concentration, often exceeding \(15\%\) to \(20\%\) in the first milking.
This elevation is primarily due to a high concentration of whey proteins, specifically immunoglobulins (such as IgG, IgA, and IgM), which are transferred from the maternal bloodstream to provide passive immunity to the newborn.
These immunoglobulins are globular proteins that lack the heat-stable open structure of caseins.
Upon heating (even at temperatures as low as \(60\text{--}65^\circ\text{C}\)), these proteins denature, unfold, and expose hydrophobic groups.
This leads to rapid self-association and the formation of a firm coagulum, causing colostrum to clot or curdle on boiling.

Step 3: Final Answer:
Colostrum has extremely low heat stability due to its exceptionally high concentration of immunoglobulins and total protein.