Question

Which one of the following is the resazurin reduction time in raw milk for production of sweetened condensed milk?

• A. < Munsell PBP 7/5.5 in h
• B. > Munsell PBP 7/5.5 in h
• C. < Munsell PBP 7/5.5in min
• D. > Munsell PBP 7/5.5in sec

Hint:

Resazurin Quality Standards: Munsell PBP 7/5.5 reading after 1 hour incubation indicates Grade A high-quality milk suitable for condensed and evaporated milk.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Standard Resazurin Test for condensed milk grading: high quality incoming milk must resist reduction past Munsell Purple-Blue-Pink standard disc 7/5.5 for greater than 1 hour ($> 1\text{ h}$).

Step 2: Detailed Explanation:
In milk grading and condensed milk manufacturing quality standards:
- Sweetened Condensed Milk (SCM) requires premium bacteriological raw milk quality to prevent age-thickening, sweet curdling, and button formation during storage.
- In the Standard 1-Hour Resazurin Reduction Test using a Lovibond comparator disk:
- Raw milk acceptable for condensed milk processing must maintain a high oxidation-reduction state with a reading greater than the Munsell color standard PBP 7/5.5 at 1 hour ($> \text{Munsell PBP 7/5.5 in h}$), indicating low initial bacterial contamination ($< 200,000\text{ cfu/mL}$).

Step 3: Final Answer:
Thus, the reduction time standard is > Munsell PBP 7/5.5 in h, corresponding to option (B).