Question

The selective criteria for Cheddar cheese cultures are-
A. Rapid acid production
B. Bacteriophage resistance
C. Salt senstivity
D. Ripening activity
Choose the correct answer from the options given below:

• A. A, B and D only
• B. A, B and C only
• C. A, B, C and D
• D. B, C and D only

Hint:

For any cheese culture, think about what it needs to do its job: be a fast worker (rapid acid), be tough (phage resistance), survive the conditions (salt tolerance), and contribute to the final product (ripening). "Salt sensitivity" is the opposite of a desired trait.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks for the desirable characteristics (selection criteria) for the starter cultures used in the manufacturing of Cheddar cheese.
Step 2: Detailed Explanation:
Let's evaluate each criterion:
A. Rapid acid production: This is critical. A predictable and fast rate of acid production is needed to control the cheese-making process, expel whey (syneresis), and achieve the correct texture and pH for cheddaring. This is a desired trait.
B. Bacteriophage resistance: Bacteriophages (or 'phages') are viruses that infect and kill bacteria. A phage infection can wipe out the starter culture, leading to slow or no acid production, which results in a failed batch of cheese. Therefore, resistance to phage attack is a vital criterion. This is a desired trait.
C. Salt senstivity: This is an undesirable trait. During Cheddar manufacturing, a significant amount of salt (around 2-3%) is added to the curd. The starter culture must be salt-tolerant to survive this step and continue its function during the initial stages of ripening. Salt sensitivity would be a reason to reject a culture.
D. Ripening activity: After the cheese is made, the enzymes released by the starter bacteria play a crucial role in breaking down proteins and fats during the aging (ripening) period. This enzymatic activity is what develops the characteristic sharp flavor and texture of mature Cheddar. This is a desired trait.
Therefore, the important criteria are rapid acid production, bacteriophage resistance, and ripening activity.
Step 3: Final Answer:
The correct selective criteria are A, B, and D.