Question

The organisms which can survive as well as multiply in the pasteurization temperature in milk are known as

• A. Psychrotrophs
• B. Thermodurics
• C. Thermophiles
• D. Mesophiles

Hint:

Thermoduric bacteria survive pasteurization but do not grow at high temperatures. Thermophilic bacteria survive pasteurization and grow at high temperatures.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Bacteria are classified into physiological groups based on their temperature requirements for survival and growth.

Step 2: Detailed Explanation:
Thermophiles are organisms with high optimal growth temperatures, typically between $55^{\circ}\text{C}$ and $65^{\circ}\text{C}$.
During low-temperature long-time (LTLT) pasteurization ($63^{\circ}\text{C}$ for 30 minutes), these organisms are able to survive and actively multiply.
Examples include Streptococcus thermophilus and Anoxybacillus flavithermus.
Other options:
Thermoduric bacteria can survive pasteurization temperatures (often as spores, like Bacillus or Clostridium species), but they cannot actively multiply or grow at these elevated temperatures; their optimum growth temperature is lower.
Psychrotrophs grow at low refrigeration temperatures ($<7^{\circ}\text{C}$) and are destroyed by pasteurization.
Mesophiles grow best at intermediate temperatures ($30^{\circ}\text{C}$ to $37^{\circ}\text{C}$) and are inactivated by standard pasteurization.

Step 3: Final Answer:
Organisms that survive and multiply at pasteurization temperatures are thermophiles.