Question

P\(_{\text{H}}\) of normal fresh milk is between

• A. 6.1 to 6.3
• B. 7.1 to 7.3
• C. 6.0 to 6.1
• D. 6.6 to 6.8

Hint:

Remember that fresh milk is slightly acidic, with a pH just below neutral (7.0). Any significant deviation from the 6.6-6.8 range indicates a problem: lower pH suggests bacterial spoilage, while higher pH (alkaline) can be a sign of mastitis.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The question asks for the normal pH range of fresh milk. pH is a measure of acidity or alkalinity. A pH of 7 is neutral, below 7 is acidic, and above 7 is alkaline.
Step 2: Detailed Explanation:
Freshly drawn milk from a healthy cow is slightly acidic. This natural acidity is not due to lactic acid but is a result of the presence of components like casein proteins, acid phosphates, citrates, and dissolved carbon dioxide.
The accepted normal pH range for fresh cow's milk is typically 6.5 to 6.7. For buffalo milk, it is slightly lower, around 6.7 to 6.8.
Let's analyze the options:
(A) 6.1 to 6.3: This pH is too low and would indicate significant developed acidity (souring).
(B) 7.1 to 7.3: This is alkaline and could be an indication of mastitis, an udder infection.
(C) 6.0 to 6.1: This is very acidic; the milk would be sour.
(D) 6.6 to 6.8: This range correctly encompasses the normal pH values for both cow and buffalo milk.
Step 3: Final Answer:
The pH of normal fresh milk is in the slightly acidic range of 6.6 to 6.8.