Question

Given below are two statements:
Statement (I): Chances of survival of thermodurics are relatively more in HTST when compared to holder method of pasteurization.
Statement (II): Control of thermoduric species is an operational problem involving both dairy farms and milk plant.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are true.
• B. Both Statement (I) and Statement (II) are false.
• C. Statement (I) is true but Statement (II) is false.
• D. Statement (I) is false but Statement (II) is true.

Hint:

To remember this:
- Cumulative heat lethality: Batch/Holder ($63^\circ\text{C}/30\text{ min}$) is physically more destructive to certain heat-resistant vegetative cells than HTST ($72^\circ\text{C}/15\text{ s}$).
- Farm to Plant: Thermodurics enter at the farm (soil/udders) and survive in the plant (pasteurizers).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Thermoduric bacteria are microorganisms that can survive high-temperature processing, such as pasteurization, but cannot grow at those elevated temperatures.
Understanding their thermal survival patterns and contamination pathways is critical for maintaining milk quality.
Detailed Explanation:
Let us evaluate Statement (I): "Chances of survival of thermodurics are relatively more in HTST when compared to holder method of pasteurization."
This statement is correct.
The holder (or batch) method of pasteurization subjects milk to $63^\circ\text{C}$ for a prolonged period of 30 minutes.
This long exposure time exerts a higher cumulative thermal lethality on microorganisms compared to the High-Temperature Short-Time (HTST) method, which exposes milk to $72^\circ\text{C}$ for only 15 seconds.
Certain thermoduric strains (such as Microbacterium lacticum, certain micrococci, and bacterial spores) can survive the brief 15-second exposure of HTST more easily than the sustained heat of the holder method.
Now let us evaluate Statement (II): "Control of thermoduric species is an operational problem involving both dairy farms and milk plant."
This statement is also correct.
Thermoduric bacteria primarily enter raw milk at the dairy farm.
Their main sources are soil, silage, bedding, and poorly cleaned milking equipment, where they can form resilient biofilms.
If raw milk with a high thermoduric count is sent to a processing plant, these bacteria survive pasteurization and can colonize pasteurizers and downstream piping, forming biofilms inside the milk plant.
Therefore, controlling thermodurics requires a coordinated effort, including strict hygienic milking practices and equipment sanitation at the farm, along with rigorous Cleaning-in-Place (CIP) protocols at the processing plant.

Step 2: Final Answer:
Both Statement (I) and Statement (II) are true.