Question

Using a high concentration of salt or sugar helps preserve foods mainly by:

• A. Lowering the pH significantly
• B. Adding a sterilizing effect
• C. Reducing the water activity
• D. Providing a surface sanitizer

Hint:

Think: Salt/Sugar = Less water = Less microbial growth. A common method for preserving fruits, meats, and vegetables.

Answer 1

The Correct Option is C

The preservation of food using high concentrations of salt or sugar is a well-established method, known as osmosis.
By adding salt or sugar, we create an environment with a high solute concentration, which draws water out of microbial cells. This process reduces the amount of free water in the food, which inhibits the growth of spoilage-causing microorganisms.
The key mechanism is reducing water activity, which refers to the amount of water available for microbial growth. With less available water, microorganisms cannot thrive, which extends the shelf life of the food.
Let’s evaluate the incorrect options:
- Lowering the pH significantly is not the primary mechanism. While salt or sugar can lower pH in some cases (e.g., in pickling), it’s the water activity reduction that plays the most critical role in preservation.
- Adding a sterilizing effect is not accurate. Salt and sugar do not sterilize; they merely inhibit microbial growth.
- Providing a surface sanitizer is incorrect. Salt and sugar preserve food through osmotic pressure, not by sanitizing surfaces.
Thus, the correct answer is the reduction of water activity.