Hygroscopicity of Anacardium othonianum Rizz. seeds

Studies on conservation and exploitation of the Brazilian Savannah native species are essential to technologies that lead to the rational exploitation of these products. This study aimed at determining the desorption isotherms of Anacardium othonianum seeds for different temperature and water activity conditions, as well as adjusting different mathematical models to the experimental data, by selecting the one that best represents the phenomenon. The hygroscopicity was determined with the aid of the gravity static method, for temperatures of 25ºC, 30ºC, 35ºC and 40ºC and water activity between 0.12 and 0.89 (decimal). It was observed that the equilibrium moisture content decreased while the temperature increased, for the same water activity, similarly to what happens with hygroscopic products. The Chung-Pfost model reached the highest determination coefficient and the lowest values for relative average error, estimated medium error and chi-square test, being the one selected to predict the hygroscopic equilibrium of Anacardium othonianum seeds. The isosteric heat increased, while the moisture content decreased, i.e., it increased the energy required to remove water, varying from 4,586.35 kJ kg-1 to 2,572.7 kJ kg-1, for the moisture content of 1.76-6.56 (d.b. %)