Question

Low temperature, preserves food by :

• A. Killing microorganisms through denaturation of proteins and inactivation of enzymes
• B. Preventing the entry of disease causing and spoilage organisms
• C. Decreasing the rate of chemical and enzymatic reactions.
• D. Stoping the growth and activity of the microorganism by interfering with the cell membrane or the enzyme activity

Hint:

Remember that cold is biostatic, meaning it "stops time" for microbes by slowing down their metabolic chemistry, whereas heat is biocidal, meaning it physically destroys (denatures) cell structures.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Food preservation techniques aim to extend the shelf life of food by preventing microbial growth and slowing down chemical deterioration.
Preservation methods can be biocidal (killing pathogens) or biostatic (inhibiting growth without killing).

Step 2: Detailed Explanation:
Low-temperature preservation (refrigeration and freezing) operates on thermodynamic and biochemical principles:
- It is a biostatic method that does not sterilize or kill the majority of food spoilage microorganisms.
- Instead, lower temperatures reduce the kinetic energy of molecules, which significantly slows down biochemical and enzymatic reaction rates inside bacterial cells and the food matrix itself.
- This microbial dormancy effectively halts cell division and stops the secretion of hydrolytic enzymes that cause spoilage.
Let us analyze why other options are incorrect:
- Option (A): Describes high-temperature preservation (such as canning or pasteurization), which denatures proteins and permanently kills microorganisms.
- Option (B): Describes aseptic packaging or physical barriers, not the chemical preservation mechanism of cold.
- Option (D): Describes chemical preservatives or radiation that directly damage cellular membranes.
Thus, the primary preservation mechanism of low temperature is reducing chemical and enzymatic reaction rates.

Step 3: Final Answer:
Low temperature preserves food primarily by decreasing the rate of chemical and enzymatic reactions.