Question

Factor considered constant in a moisture sorption isotherm, is ________. 
 

• A. Water activity
• B. Moisture content
• C. Temperature
• D. Total solids

Hint:

The word "isotherm" comes from the Greek words "iso" (equal) and "therme" (heat). Therefore, any thermodynamic "isotherm" represents a system held at a constant temperature.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
A moisture sorption isotherm plots the relationship between equilibrium moisture content and water activity of a food product.
By definition, "isotherm" refers to a process or curve plotted at a constant temperature.
Detailed Explanation:
- A moisture sorption isotherm plots the equilibrium moisture content ($M$, on the y-axis) against water activity ($a_w$, on the x-axis).
- Because temperature affects the water-binding capacity of food components, the relationship between $M$ and $a_w$ changes as temperature changes.
- To isolate the effect of water activity on moisture content, the measurement must be conducted at a single, constant temperature (C).
- If the temperature changes, a new isotherm curve must be generated.

Step 2: Final Answer:
The factor held constant in a moisture sorption isotherm is temperature.