Question

Why are spore-forming bacteria a particular concern in raw milk?

• A. They can survive pasteurization and other heat treatments.
• B. They can cause changes in the pH of milk.
• C. They contribute to increased somatic cell counts.
• D. They indicate the presence of coliform contamination.

Hint:

Bacterial endospores are the most heat-resistant biological structures known. Standard pasteurization does not destroy them, which limits the shelf-life of pasteurized milk.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Spore-forming bacteria (such as Bacillus and Clostridium species) can form dormant, highly resistant structures called endospores under unfavorable environmental conditions.

Step 2: Detailed Explanation:
- Endospores are highly resistant to heat, dehydration, radiation, and chemical sanitizers.
- During standard pasteurization (\(72^{\circ}\text{C}\) for 15 seconds) or other mild heat treatments, vegetative bacterial cells are killed, but endospores survive.
- Once the milk cools down, these surviving spores can germinate back into active vegetative cells, multiplying to cause spoilage (e.g., sweet curdling, bitty cream) or foodborne illness.
- While vegetative cells can alter the pH, the primary concern with spore-formers is their extreme heat resistance. They are not indicators of coliform contamination and do not affect somatic cell counts in the udder.

Step 3: Final Answer
Spore-formers are a major concern because they survive pasteurization and other heat treatments.