Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : In UHT sterilization treatments spore destructions is higher while chemical changes are minimal.
Reason (R) : The \(Q_{10}\) value for bacterial endogens ranges between 8 to 30 while the \(Q_{10}\) value for chemical changes is 1.5 -- 2.0.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Hint:

The fundamental principle of all High-Temperature Short-Time (HTST) and UHT processes is:
\[ Q_{10, \text{ microbial destruction}} \gg Q_{10, \text{ chemical reaction}} \] This difference allows thermal sterilization with minimal loss of nutritional quality.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Ultra-High Temperature (UHT) processing is based on the kinetic differences in heat inactivation of bacterial spores versus chemical degradation reactions in milk.
The temperature coefficient, denoted as \(Q_{10}\), represents the factor by which a reaction rate increases when the process temperature is raised by \(10^\circ\text{C}\).

Step 2: Detailed Explanation:
Let us evaluate both the Assertion and the Reason:
- Assertion (A) is correct: UHT processing (heating milk to \(135\text{--}150^\circ\text{C}\) for \(2\text{--}5\) seconds) successfully achieves commercial sterility (spore destruction) while preserving the natural flavor, color, and nutritional value of milk (minimal chemical changes) compared to batch retorting.
- Reason (R) is correct and explains (A):
The reaction rate for spore destruction is highly temperature-dependent, possessing a high activation energy. This is reflected in a very high \(Q_{10}\) value of 8 to 30 (typically around \(10\text{--}20\) for bacterial endospores).
Conversely, chemical reactions such as vitamin destruction, lipid oxidation, and the Maillard browning reaction have lower activation energies, corresponding to a much lower \(Q_{10}\) value of 1.5 to 2.0.
When the temperature is raised, the rate of spore destruction increases exponentially at a much faster rate than the rate of chemical degradation.
Therefore, by operating at extremely high temperatures for a very short holding time, we can maximize spore destruction while minimizing chemical damage.

Step 3: Final Answer:
Both Statement (A) and Reason (R) are correct, and (R) is the direct kinetic explanation of (A).