KINETICS OF OSMOTIC DEHYDRATION IN ORANGE AND MANDARIN PEELS

The nutritional and health properties of some citrus peel components such as pectin, flavonoids, carotenoids or limonene make interesting developing processing methods to obtain peel stable products, maintaining its quality attributes, increasing its sweetness and improving its sensory acceptability. In this sense, osmotic dehydration represents a useful alternative by using sugar solutions at mild temperature. Kinetics of osmotic treatments of orange and mandarin peels carried out at atmospheric pressure and by applying a vacuum pulse at the beginning of the process were analysed at 30, 40 and 50C, in 65 °Brix sucrose, 55 °Brix glucose and 60 °Brix rectified grape must. Vacuum pulse greatly affected mass transfer behavior of peels due to the greatly porous structure of albedo. So, PVOD treatments greatly accelerate the changes in the product composition in line with an increase in the peel sample thickness. In osmotic processes at atmospheric pressure, sample impregnation occurs coupled with osmotic process, but much longer treatments are required to achieve a reasonable concentration degree which assures sample stability. Low viscosity osmotic solutions seems recommendable in order to promote both diffusional and hydrodynamic transport, in vacuum pulsed pretreatments at mild temperatures. La deshydratation osmotique represente une alternative interessante au traitement thermique en utilisant des solutions sucrees a temperature faible. Cette etude examine les cinetiques de deshydratation osmotique d'ecorces d'orange et de mandarine. L'objectif est d'analyser l'influence de quelques facteurs comme la temperature, un agent osmotique, un vide prealable, sur le comportement de transfert d'eau et de solutes, pour identifier les conditions optimales de transformation.