Physicochemical and sorption isotherm properties of date syrup powder: Antiplasticizing effect of maltodextrin

In this research, date syrup powder was produced using a twin drum dryer. Maltodextrin with dextrose equivalent of 19, as an antiplasticizer, was added to date syrup at various concentrations (30, 40, 50 and 60%, dry basis of date syrup) to improve its drying properties. Some physicochemical properties of the powders including degree of caking, density, color, glass transition temperature and sorption isotherms were studied and compared. Powder density, lightness and glass transition temperature increased with maltodextrin level. However, "a" color value and degree of caking decreased as maltodextrin increased. Moisture sorption isotherms were obtained at 5-60°C and the data were modeled to BET, GAB, and Peleg models and GAB and Peleg were found as suitable models to fit moisture sorption data. Monolayer moisture content decreased with maltodextrin level from 0 to 60% as calculated from BET and GAB models. All date syrup powders showed type III isotherms similar to that of high-sugar foods. Maltodextrin acted as antiplasticizer in date syrup drying and date syrup powder of low caking property was produced successfully.