OSMOTIC EVAPORATION OF TOMATO JUICE BY USING CaCl2.6H2O AND MgCl2.6H2O AS OSMOTIC SOLUTION

Abstract

The osmotic pressure (atm.) of tomato juice at different concentrations and temperatures were determined. Two kinds of salts, namely, CaCl2.. 6H2O and MgCl2.6H2O were used as osmotic solutions with different molarities, temperatures and periods. The total soluble solids (TSS) in tomato juice was adjusted to 4.5%.The development in total soluble solids percentages by using 1, 2, 3, 4 and 5 M osmotic solutions at 25, 30 , 35 , 40 , 45 and50o C , for 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165 and 180 min. were determined. Using the selected molarities; 1, 2, 3, 4, 5 M CaCl2.6H2O as osmotic solution and running the process from 15 to 180 min., the total soluble solids (TSS%) in tomato juice have developed from 8.1 to 23.1% at 25o C; 9.1 to 24.1% at 30o C; 9.9 to 24.9% at 35o C; 10.5 to 25.5% at 40o C; 11.0 to 26.0% at 45o C and 11.4 to 26.5 at 50o C, respectively. Repeating the experiment with MgCl2.6H2O as osmotic solution the total soluble solids (TSS %) in tomato juice have developed from 10.8 to 30.7% at 25o C; 12.1 to 32.1% at 30o C; 13.2 to 33.1% at 35o C; 14.0 to 33.9% at 40o C; 14.6 to 34.6% at 45o C and 15.2 to 35.2% at 50o C respectively. The water fluxes declines in juice, in the course of osmotic evaporation processes had been studied. The final products were judged by the team work itself. The sensory evaluation of taste, odor and color has shown similar values in rediluted concentrations as compared with fresh juices. A loss between 16-24% in ascorbic acid content is associated with osmotic evaporation process, especially at high temperatures (45 and 50o C).