Mass transfer kinetics during osmotic dehydration of carrot cubes in sugar beet molasses

The paper describes the effect of different solution concentrations ( 80, 60 and 40%) and immersion time on osmotic dehydration/impregnation of carrot cubes in sugar beet molasses as hypertonic solution. Osmotic dehydration process was conducted at the temperature of 45 degrees C and under atmospheric pressure. The highest value of dry matter content, in osmodehydrated carrot (54.67%), was achieved when 80% sugar beet molasses was used as osmotic solution. Mass transfer coefficients (k(w) and k(s)) were calculated using equations proposed by Hawkes and Flink's. Using the LabFit Curve Fitting Software, mathematical equation that fits the calculated mass transfer coefficients was determined. The proposed equation has three parameters and takes into account both variables (time and concentration). That equation satisfactory fits experimental data and high values of correlation coefficients were reached (R = 0.9665 for k(w) and R = 0.9306 for k(s)). In the second experiment, influence of the osmotic solution circulation on the final dry matter content was examined. It was found that the dry matter content, after 5 h of dehydration, was considerably higher if the process took place under conditions of osmotic solution circulation.