Question

Which of the following represents the SPC (in cfu per ml, after rounding off as per standard procedure) and grade, respectively of the given sample?

• A. 2,45,000 and Fair
• B. 2,50,000 and Good
• C. 2,40,000 and Good
• D. 2,50,000 and Very good

Hint:

BIS Raw Milk SPC Grading Scale:
$< 200,000\text{ cfu/mL}$ = VERY GOOD.
$200,000 - 1,000,000\text{ cfu/mL}$ = GOOD (2,50,000 cfu/mL).
$1,000,000 - 5,000,000\text{ cfu/mL}$ = FAIR.
$> 5,000,000\text{ cfu/mL}$ = POOR.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Standard Plate Count (SPC) reporting and raw milk bacteriological grading rules: raw colony counts are rounded to two significant digits (e.g., 2,45,000 rounds to 2,50,000 cfu/mL), and raw milk containing 200,000 to 1,000,000 cfu/mL is officially graded as 'Good'.
Key Formula or Approach:
\[ \text{BIS Raw Milk Grading: Very Good } ( 5\text{ M}) \]

Step 2: Detailed Explanation:
According to standard microbiological reporting rules (Standard Methods for the Examination of Dairy Products - APHA) and Indian Standards (BIS FSSAI Raw Milk Grading):
1. Rounding-Off Rule (APHA ISO Standards): When reporting bacterial colony counts, the calculated value is rounded off to two significant figures. When the third digit is 5, it is standardly rounded to the nearest even hundred thousand, rounding $2,45,000\text{ cfu/mL}$ to 2,50,000 cfu/mL.
2. Bacteriological Grading of Raw Milk (BIS: 1479 Standards):
- Very Good: $< 200,000\text{ cfu/mL}$
- Good (B): 200,000 to 1,000,000 cfu/mL (encompassing $2,50,000\text{ cfu/mL}$).
- Fair: $1,000,000\text{ to } 5,000,000\text{ cfu/mL}$.
- Poor: $> 5,000,000\text{ cfu/mL}$.
- Therefore, the rounded SPC and grade is 2,50,000 and Good.

Step 3: Final Answer:
Thus, the correct representation is 2,50,000 and Good, corresponding to option (B).