Effect of osmotic dehydration on color and sorption characteristics of apple and banana

Color and sorption characteristics of osmotically treated and air dried app le and banana were studied during air drying at 70 degrees C. The color par ameters: Lightness (L), Redness (a) and Yellowness (b) were studied, using a Hunter Lab chromatometer. ii first order kinetic model was fitted to the experimental data adequately for color parameters, while sorption data for treated and air dried products were fitted to the GAB model. Untreated frui ts showed an extensive browning which was monitored by a significant drop o f the lightness (L) and an increase of redness (a) and yellowness (b). Osmo tically pretreated samples did not brown as much as the untreated samples a nd the lightness L decreased only slightly while a, b increased slightly. O smotic pretreatment resulted in a shift in sorption isotherm for both fruit s. Osmotic dehydration prevented color damages and decreased the sorption c apacity of dehydrated products.