Effect of glycerol on the moisture sorption isotherms of figs

In this research the effects of glycerol (at 20% and 40%, w/w) on moisture sorption isotherms of dried figs at 5, 25, and 40 °C were studied. Glycerol had notable effects on the sorption isotherms. The comparison of the samples with and without glycerol showed that at a specific water activity the samples with glycerol contained higher moisture contents. Fitting the experimental data obtained to well known GAB and BET models revealed that these two equations were able to give good fits with R2 of >0.99. The addition of glycerol significantly increases the monolayer water levels of fig–glycerol systems. In addition, glycerol changes the shape and status of the sorption isotherms of figs from sugar type isotherm to sigmoidal shape which is typical of most food systems.