2.5. Sorption isotherm curves using dynamic vapour sorption
DVS (dynamic vapour sorption) is a relatively novel technique to
the food industry. The technique enables the study of hydration and
dehydration of a material by monitoring changes in mass when the
sample is subjected to different relative humidities. It is a ‘dynamic
equilibration method,’ i.e. relies on the continuous circulation of RH
controlled gas over the sample, and hence is relatively rapid as
compared to static equilibration methods. The required humidity is
achieved by mixing dry and water-vapour-saturated nitrogen gas
flows, with the help of flow controllers, before they enter the
chambers (Teoh, Schmidt, Day, & Faller, 2001). Using this method of
obtaining humidified gas can achieve relative humidity values
ranging from 0 to 95% RH. This gas then exits the chambers above
the pans.
3. Results and discussi