Moisture sorption characteristics and modelling of babool ( Acacia nilotica ) gum

Background The study of sorption isotherm is the most important for prediction of shelf life, selection of packaging materials, drying characteristics, etc., of any food and agricultural materials. Gum is hygroscopic in nature, so finding of moisture sorption is crucial. Equilibrium moisture content of babool gum at 30, 40, 50 and 60 °C temperatures under relative humidity ranging from 11 to 95% was determined. Results Maximum equilibrium moisture content (EMC) of babool gum (33.6%, db) was recorded with the set of highest relative humidity (92.3%) at lowest temperature (30 °C), and minimum (2.8%, db) was obtained with the set of lowest relative humidity (10.9%) at highest temperature (60 °C) under the experimental conditions. The EMC data were employed in five well-identified sorption models, namely GAB, Iglesias and Chirife, Caurie, Halsey and BET model. GAB model best interpreted the data in a reasonable way as per statistical parameters of goodness of fit. The monolayer moisture content M o was found to be 8.46 and 7.49 g/100 g at 30 and 60 °C, respectively. Conclusion The sorption behaviours of babool gum were classified as type-II curves. It was obviously perceived that the isosteric heat decreases with the boost in moisture content.