Question

What is the moisture content level below which most bacteria cannot grow in dried foods?

• A. 50%
• B. 30%
• C. 15%
• D. 5%

Hint:

While bacteria are inhibited at low moisture, some molds and yeasts can still grow, so proper storage is still important.

Answer 1

The Correct Option is C

Concept: Microbial growth in foods is highly dependent on the availability of water, often expressed as moisture content or water activity ($a_w$). Bacteria generally require higher moisture levels compared to molds and yeasts. In dried foods, reducing moisture content inhibits microbial growth and enhances shelf life. Most bacteria cannot grow effectively when moisture content falls below a certain threshold.
Step 1: Understand moisture requirements of bacteria.

• Bacteria require high moisture levels for growth
• They are more sensitive to low moisture than molds and yeasts

Step 2: Interpret the critical moisture level.
When moisture content drops below approximately 15%, conditions become unfavorable for most bacterial growth.
Step 3: Select the correct option.
Thus, 15% is the threshold below which most bacteria cannot grow in dried foods.