Question

Given below are two statements
Statement I: Bactofugation process removes almost all bacterial cells and spores including heat resistant spores from milk and provides a biologically clean environment for making good quality cheese.
Statement II: Bactofugation prevents late blowing defect in semi-hard or hard variety of cheeses due to removal of anaerobic microorganisms. This process weakens the coagulum during cheese making which can be overcome by addition of calcium chloride.
In light of the above statements, choose the correct 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:

Bactofugation uses centrifugal force to separate dense bacterial spores (such as Clostridium) from milk, preventing late blowing in hard cheeses. Any minor weakening of the curd is corrected by adding calcium chloride.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Bactofugation is a specialized centrifugal process used in dairy plants to remove high-density microorganisms and bacterial spores from milk.
Because bacterial spores have a higher density ($1.2$ to $1.3 \text{ g/cm}^3$) than milk serum ($1.03 \text{ g/cm}^3$), they can be separated by applying intense centrifugal force.
This mechanical separation is particularly useful in cheesemaking to remove heat-resistant spores that survive pasteurization.

Step 2: Detailed Explanation:
Statement I describes the function of bactofugation.
By applying high-speed centrifugal force, a bactofuge can remove up to 98% to 99% of bacterial spores and up to 95% of vegetative cells from milk.
This provides a biologically clean milk supply without using severe heat treatments that would denature whey proteins and impair cheesemaking properties.
Thus, Statement I is true.
Statement II describes the technological benefits and consequences of bactofugation.
The removal of anaerobic spore-formers, particularly Clostridium tyrobutyricum, is essential to prevent the "late blowing" defect in aged semi-hard and hard cheeses (such as Gouda or Emmental).
This defect is caused by clostridia fermenting lactic acid to produce butyric acid, carbon dioxide, and hydrogen gases, which create large, irregular holes and off-flavors in the cheese.
However, the high shear force and temperature used during bactofugation can cause slight physical changes in the casein micelles, which can weaken the subsequent rennet coagulum.
This minor structural weakening is easily overcome by adding a small amount of calcium chloride ($CaCl_2$) to the treated milk to restore curd firmness.
Thus, Statement II is true.
Therefore, both statements are true.

Step 3: Final Answer
Both Statement I and Statement II are true.