Sorption isotherm behavior of osmoconvectively dehydrated carrot cubes

Carrot cubes, osmotically pretreated with aqueous sodium chloride (10%, w/v), sucrose syrup (55 degrees Brix), and mixture of sucrose and sodium chloride (50 degrees Brix + 10%, w/v), were convectively dehydrated at 65C temperature up to final moisture content of 4-5% (wet basis). To study their equilibrium moisture content (EMC) behavior, the dehydrated carrot cubes were stored at temperature ranging from 10 to 50C and relative humidity ranging from 15-95% using static desiccator technique. Five isotherm equations, viz, Chung-Pfost, modified Henderson, modified Halsey, modified Oswin and modified exponential were applied to examine the data. Among the applied models, modified Oswin model was best fit for control (untreated) and salt-treated samples, modified Hesley model for sucrose-treated samples and two-term exponential model for mixture of sucrose-salt treatment over the entire range of relative humidity and temperature. The EMC values of cubes osmotically pretreated with sodium chloride solution were highest among all pretreatments, and were lowest for control (unosmosed) samples.