Physical and chemical changes in guava raisin (Psidum guajava l.) produced by osmotic dehydration and drying convective

Abstract

The osmotic dehydration pre-treatment is used to partially reduce the fruit initial water content, before convective drying. Purpose of the present work is to investigate the influence of osmotic treatment followed by convective drying on the physicochemical parameters of guava slices. The Paluma guava was cut into slices of 3.0 x 2.0 x 0.9 cm, dehydrated and dipped in sucrose syrup at concentrations of 40, 50 and 60° Brix, at temperatures of 30, 40 and 50° C. The process was again supplemented by convective drying at temperatures of 50, 60 and 70° C. Guava-raisins with and without pre-osmotic treatments were subjected to the following physico-chemical analyzes: soluble solids, pH, total acidity, ash, reducing and total sugars, water activity (Aw). The color was considerably changed into a darker and the total sugar reduced as a result of the syrup concentration and osmotic dehydration temperatures. Also, the pH and Aw decreased through application of treatments. From the results it is recommended that the production of guava passes under dehydrating conditions of 60° Brix at 50° C and further drying temperature of 60° C is efficient.