Subtopic: Water activity, sorption and desorption isotherms
Question Statement:
Most agricultural and starchy food products (such as grains, flours, and pulses) exhibit which type of BET moisture sorption isotherm classification?
Options:
(A) Type II (Sigmoidal S-shaped isotherm)
(B) Type I (Langmuir monolayer isotherm)
(C) Type III (Flory-Huggins solvent swelling isotherm)
(D) Type V (Capillary condensation on porous non-wetting adsorbents)
Answer Key:
A
Step-by-Step Solution & Explanation
Starchy and protein-rich agricultural food products exhibit Type II sigmoidal sorption isotherms. The curve shows an inflection representing the completion of a monomolecular water layer (Zone I), followed by multimolecular layer adsorption (Zone II), and capillary condensation of free water at high water activities (Zone III).