The isosteric heat of sorption varied between 5.22 and 1.12 KJ/mol at moisture level varying between 1 and 9 % db.
The isosteric heat of sorption curve showed a fall with increase in moisture content and approached the heat of vaporization of free water at higher moisture content. The elevated values of heat of sorption of water at low moisture contents are an
indication of strong water–food component interactions by the existence of polar groups on the surface of the product.