Efecto del Escaldado sobre la Deshidratación Osmótica del Mango

Abstract

Combined treatments, such as blanching, osmotic dehydration at atmospheric pressure (OD) and pulsed vacuum osmotic dehydration (PVOD) to improve food quality (sensorial and nutritional) are a useful practice in fruit processing. Blanching reduces enzyme activity and improves color in some cases. Water activity reduction by osmodehydration (OD) with concentrated sugar/salt solutions, at low temperature, allows us to obtain minimally processed fruit or to reduce freezable water in order to improve frozen preservation. In this work, the influence of steam blanching pretreatment of mango (var. Kent) for 1.5 min on the kinetics of osmotic dehydration and pulsed vacuum osmotic dehydration was analyzed. Treatments were carried out at 30ºC with 59.3 Brix sucrose solution. At several times of processing (till 5 h) samples were analyzed as to weight and volume changes and moisture and soluble solid concentration and water activity. Kinetics of sugar and water net gains were analyzed as well as changes in the fruit liquid phase (FLP: water plus soluble solids) composition. Development of volume changes, density and water activity of the samples in the different treatments was compared. PVOD treatments show faster kinetics in solute and water gains, and slightly higher values of effective diffusivity in the FLP, especially in blanched samples. Volume changes in OD treatments were fully explained in terms of the FLP volume changes. In PVOD treatments, deviations from this behavior were observed due to sample impregnation-deformation during vacuum pulse.