A Survey of Temperature Effects on GAB Monolayer in Foods and Minimum Integral Entropies of Sorption: a Review

Some aspects of GAB monolayer values in foods were reviewed. Literature data on the stoichiometry of water sorption by proteins and other biopolymers were re-analyzed and a good linear correlation ( r 2 = 0.8431) between the number of polar groups and the GAB monolayer was obtained. This helps to corroborate the hypothesis that each polar group initially adsorbs a water molecule. A survey of GAB monolayers at various temperatures in more than 70 different food products indicated that for most of them – although not all – an increase in temperature produced a decrease in the value of moisture content (g water/100 g solids) corresponding to the monolayer. However, in an appreciable number of cases, it was observed that the monolayer remained constant or increased with temperature. The relationship between the minimum integral entropy (MIE) and the GAB monolayer was studied using literature data. For 38 different food products, the regression curve ( r 2 = 0.9038) between the moisture content corresponding to MIE and GAB monolayer was close to the 45° diagonal, suggesting that GAB values matched the position of minimum integral entropy. However, for a wide variety of other products, the moisture of the MIE was located above that of the monolayer.