Moisture sorption isotherm
At equilibrium, the relationship between water content and equilibrium humidity of a material can be displayed graphically by a curve, the so called moisture sorption isotherm. For each humidity value, a sorption isotherm indicates the corresponding water content value at a given, constant temperature. If the composition or quality of the material changes, then its sorption behaviour also changes. Because of the complexity of sorption processes, the isotherms cannot be determined by calculation, but must be recorded experimentally for each product.
The relationship between water content and water activity (aw) is complex. An increase in aw is usually accompanied by an increase in water content, but in a non-linear fashion. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm. These curves are determined experimentally and constitute the fingerprint of a food system.
Bell, L.N., and Labuza, T.P. 2000. "Practical Aspects of Moisture Sorption Isotherm Measurement and Use". 2nd Edition AACC Egan Press, Egan, MN
Wikimedia Foundation. 2010.
Look at other dictionaries:
Moisture vapor transmission rate — (MVTR), also water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance. There are many industries where moisture control is critical. Moisture sensitive foods and pharmeceuticals are put in packaging… … Wikipedia
Dynamic vapor sorption — (DVS) is a gravimetric technique that measures how quickly and how much of a solvent is absorbed by a sample: such as a dry powder absorbing water. It does this by varying the vapor concentration surrounding the sample and measuring the change in … Wikipedia
Desorption — is a phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption (that is, either adsorption and absorption). This occurs in a system being in the state of sorption equilibrium between bulk phase… … Wikipedia
Water activity — or aw is a measurement of the energy status of the water in a system. It is defined as the vapor pressure of water above a sample divided by that of pure water at the same temperature; therefore, pure distilled water has a water activity of… … Wikipedia
Coal bed methane extraction — (CBM extraction) is a method for extracting methane from a coal deposit. Contents 1 Basic principles 2 Areas with coal bed methane extraction 3 Measuring the gas content of coal … Wikipedia