Question

__________ was used to describe relationship between the water activity and equilibrium moisture content.

(a) Kelvin model

(b) Harkins-Jura model

(c) Chung-Pfost model

(d) GAB model

I have been asked this question in a national level competition.

The question is from Drying in chapter Drying of Food Processing Unit Operations

Answer 1

The correct option is (d) GAB model

To elaborate: GAB modelwas used to describe relationship between the water activity and equilibrium moisture content. In Guggenheim, Anderson, de Boer (GAB) model, the sample is kept in the desiccators which contains saturated Potassium nitrate solution to maintain the relative humidity at 90% at 40°C and are kept in a temperature controlled chamber.  Moisture content and water activity of each sample is determined using hot air oven and water activity meter.