Moisture Sorption Isotherms of Edible Coated Solid Sugarcane Jaggery

The moisture sorption isotherms (MSIs) of solid sugarcane jaggery, coated with five edible coatings, namely whey protein concentrate, wheat gluten, zein, gelatine and gum arabic at three levels of concentrations, i.e. 0.5, 1.5 and 2.5%, were calculated by using the technique of static gravimetric based on isopiestic vapour transfer technique using saturated salt solutions at three levels of temperatures, i.e. 25, 35 and 45 °C. The experimental MSI data were fitted into the three models, namely Iglesias and Chirife and Modified Halsey and GAB. The isotherms for edible coated solid sugarcane jaggery samples were found Type-III isotherms. Among the three MSI models, GAB model was found to be best fit with the experimental data followed by other two models, i.e. Halsey and Iglesias and Chirife model. For the control sample (solid sugarcane jaggery samples without edible coating), the monolayer moisture content (M0) was maximum of 4.368 (%db.) at 25 °C and minimum 3.740 (%db.) at 45 °C. A decreasing trend of M0 values of the solid sugarcane jaggery samples with edible coatings was found with increase in coating concentration (0.5–2.5%) and temperature (25–45 °C). The highest value of M0, i.e. 4.886 (%db.), was found with 0.5% concentration of wheat gluten coating at 25 °C temperature.