Progressive Freeze-Concentration of Tomato Juice

Abstract

Progressive freeze-concentration was applied to concentrate tomato juice. Effective partition constants of the solute between the solid and liquid phases were experimentally determined for total solid and potassium chloride (KCl)-equivalent salts. The partition constants were strongly dependent on the stirring rate at the ice front and the advance rate of that front. Increasing stirring rate and reducing advance rate of the ice front lowered the effective partition constant and improved freeze concentration performance. The partition constant was different between total solid and salts suggesting a different mechanism in the partition phenomena between the two components. Tomato juice of 4.3 wt% in solid content was concentrated up to 18.8 wt%. After the reconstitution of freeze concentrated tomato juice based on Brix, no substantial differences, except for salt content, were observed in acidity, vitamin C content, or color quality compared with before the concentration.