Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Thermophilic group of microorganisms represent dairy plant contamination rather than farm contamination
Reason R: Unhygienic handling practices coupled with poor design and maintenance of equipment is an important cause of contamination of pasteurized milk
In the light of the above statement choose the most appropriate answer from the options given below

• A. Both A and R are correct and R is a correct explanation of A
• B. Both A and R are correct but R is NOT the correct explanation of A
• C. A is correct but R is not a correct
• D. A is not correct but R is correct

Hint:

Dairy Microbial Contamination Indices:
Thermophilic bacteria ($55-65^\circ\text{C}$) $\rightarrow$ Index of PLANT contamination (pasteurizers/evaporators).
Psychrotrophic bacteria ($4-7^\circ\text{C}$) $\rightarrow$ Index of REFRIGERATED raw milk farm bulk tank storage.
Coliforms $\rightarrow$ Index of POST-PASTEURIZATION unhygienic contamination.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Dairy processing microbiology: thermophilic sporeformers (Bacillus stearothermophilus, B. coagulans) build up bio-fouling deposits in HTST pasteurizer regeneration sections, acting as an index of plant processing equipment contamination.

Step 2: Detailed Explanation:
1. Assertion A: Thermophilic microorganisms (e.g., Geobacillus stearothermophilus, Bacillus licheniformis) grow optimally at high temperatures ($55^\circ - 65^\circ ext{C}$). Raw milk from dairy farms arrives cold ($< 4^\circ ext{C}$) and contains negligible thermophiles. However, during continuous processing runs in dairy processing plants, thermophiles attach to warm metal surfaces (pasteurizer regeneration sections, pre-heaters, evaporators) and multiply rapidly. Thus, high thermophilic counts represent dairy plant processing contamination rather than farm contamination. Hence, Assertion A is correct.
2. Reason R: Unhygienic plant sanitation, cracked gaskets, dead ends in piping, and poor maintenance allow thermophiles and post-pasteurization contaminants to form heat-resistant biofilms that contaminate pasteurized milk. Hence, Reason R is correct and directly explains A.

Step 3: Final Answer:
Therefore, Both A and R are correct and R is a correct explanation of A, matching option (A).