' ' ' ' Calculator for determining equilibrium moisture values corresponding to selected Aw values using the Brunauer-Emmett-Tellet (BET) model
Dairy science logo

    This website

 Site Coordinator | Contributors | Links | Contribute an article or link | News | Forum |


 Cheese starters


 Cheese yield

 Cheese quality

 Cheese science and technology

 Inhibitors in milk

 Cheeses of Piedmont Italy

 Exploitation of anti-microbial  proteins

 Bacteriophages for lactococci

 Primary production

 Ice cream

 Science and technology of wine

 Thermal processing

 Calculators and models

 Harvard reference generator


 Industrial microbiology

 Jobs and careers advice

 Support site

The Brunauer-Emmett-Tellet (BET) model can be used to describe how foods and other materials absorb and desorb moisture and how this affects Aw. It gives similar results in many instances to the Guggenheim–Anderson–de Boer (GAB) model and is equivalent to the GAB model when the GAB K constant =1.

I will add a tutorial later explaining the advantages of the model and how it can be used for product development and to produce moisture isotherms. The latter are required in certain jurisdictions for dried foods prior to the issue of export certificates.

To use the model you must obtain the BET constants for the product concerned. There is a significant volume of literature listing the constants for major products so you should be able to access these easily. Alternatively these can be derived using an Aw- meter. The constants are then added to the table below and the Aw values you have selected inputted. The calculator will then calculate the equilibrium moisture content for each value and plot it against Aw, to give a sorption or desorption isotherm.

To use the model you must have Java script enabled on your viewing device and have a browser that support iframes. If you cannot see the graph generated try another browser.

Note the constants for a particular food or material will normally be valid for a restricted range of Aw and moisture values.

How to cite this article

Mullan, W.M.A. (2019) [On-line] Available from: Accessed: