Hygroscopic behavior of the dry residue of pink shrimp

A study was made of the hygroscopic behavior of the dry residue of pink shrimp (Peneaus subtilis), characterized as being rich in total proteins (42.59%) and ash (22.01%). Adsorption and desorption isotherms were plotted at 10, 25 and 40 degrees C. The monolayer and desorption heat values were determined and thirteen mathematical models were fitted to experimental data to predict the sorption data. The product presented Type II isotherms. The adsorption data indicated that the product's microbiological stability (a(w) < 0.6) would require the dry residue to contain moisture of less than 13.0 g H2O.100 g(-1) dry solids in adsorption and 14.0 g H2O-100 g(-1) dry solids in desorption. The monolayer's desorption values indicated that, in order to avoid unnecessary loss of energy, the residue should not be dried to a moisture level below 7.29 g H2O-100 g(-1) dry solids. The values of desorption heat indicated that large amounts of energy were not required to dry the residue to appropriate levels of moisture to attain microbiological stability (a(w) < 0.6). The best models for predicting the sorption isotherms of the residue were Oswin and Halsey (biparametric); GAB, modified BET, Hailwood-Horrobin, Anderson, Anderson-Hall and Gascoyne-Pethig (triparametric).