Question

In pulse electric field, microbial cells are more sensitive in -

• A. Log phase
• B. Stationary phase
• C. Decline phase
• D. Death phase

Hint:

In food preservation, microorganisms in their active growth (log) phase are almost always more sensitive to both thermal and non-thermal technologies (like PEF, high-pressure processing, and UV) than those in the resting (stationary or spore) phases.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Pulsed Electric Field (PEF) is a non-thermal food preservation technology that uses short pulses of high voltage to induce electroporation (formation of temporary or permanent pores) in microbial cell membranes, leading to cell leakage and death.

Step 2: Detailed Explanation:
The physiological state and growth phase of microbial cells significantly affect their resistance to inactivation treatments:
- Log phase (exponential growth phase): The cells are actively dividing and expanding. During this phase, the cell membranes are rapidly synthesizing, thinner, and structurally less rigid compared to mature cells. This makes them highly susceptible to electric-field-induced transmembrane potentials, causing rapid electroporation and cell lysis.
- Stationary phase: The cells develop thicker, more rigid cell walls and more robust cell membranes to survive nutrient limitations, making them significantly more resistant to PEF and other stress factors.

Step 3: Final Answer:
Microbial cells are most sensitive in the Log phase, which corresponds to option (A).