Guggenheim-Anderson-De Boer

Water-sorption properties of various films were determined gravimetri-cally after storage of freeze-dried samples in vacuum desiccators at a relative humidity ranging from 11 to 86% at 25°C. Water-sorption behavior was modeled with the Guggenheim-Anderson-de Boer (GAB) Equation 24.1 in which water content is m, monolayer moisture content is wXm, water activity is flw/ arid K and C are constants. 

The Guggenheim-Anderson-de Boer (GAB) equation is considered as the most versatile model, capable of application to situations over a wide range of water activities (0.1 process analysis and design of drying because of its reliability, its simple mathematical form, and its wide use (with materials and water activity ranges). Table 4.14 lists parameter values of the GAB equation for some foods. 

Application of the Guggenheim-Anderson-de Boer Model to Some Fruits and Vegetables... 

Water activity in foods is related to moisture content using Guggenheim-Anderson-de Boer (GAB) equation ... 

Table 4.2 summarizes the isotherm equations discnssed so far pins some others, added for comparison. The first four have been discussed earlier in the text. The Guggenheim-Anderson-de Boer isotherm (GAB) is a multilayer sorption equation, a modified form of the BET equation that has found wide application in food science and technology (Timmermann 2003 and references therein). Basically, it does not consider the layers beyond the first as the liquid adsorbate but as an intermediate... 

Bratasz L, Kozlowska A, Kozlowski R (2012) Analysis of water adsorption by wood using the Guggenheim-Anderson-de Boer equation. Eur J Wood Wood Prod 70 445 51... 

The Guggenheim-Anderson-de Boer (GAB) equation is considered as the most versatile model, capable of application to situations over a wide range of water activities (0.1 < < 0.9) and to various materials... 

The TGA trace obtained from the samples is directly related to the residual water content of the sample If this is plotted versus the a obtained from the ratio of the DTG signal, the whole desorption isotherm is obtained (Figure 20) which nicely obeys either the BET(Benauer - Emmet - Teller) or GAB (Guggenheim -Anderson- de Boers) equation [118],... 

Statistical models of the sorption behavior of foods have been applied for predicting the sorption behavior of foods. One of the most well-known and used model is the equation proposed by Brunauer, Emmett, and Teller known as the BET sorption isotherm model. This model is used extensively in food research. Another model extensively used for foods proposed by Guggenheim, Anderson, and de Boer is known as the GAB model or equation. The predicted values by either... 

While increasing the relative humidity of the surrounding air, crystalline materials do not absorb significant quantities of water. Only a limited amount of crystal water is embedded in the molecular matrix. Once a substance-specific relative air humidity (or water activity) is reached, the crystals dissolve layer by layer. In contrast, amorphous water-soluble substances absorb significant quantities of water when exposed to an increasing relative humidity of the surrounding air. The amount of absorbed water is a function of the water activity that can be described by various types of isotherm equations (Guggenheim, Anderson and de Boer (GAB), Brunnauer, Emmett and Teller (BET), see Weisser (1986)). 

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