Effect of the parameters of osmotic drying on some physical properties of quince

Abstract

Osmotic drying of quince is used as the first step in combined drying. The removal of moisture during osmotic drying ensures less time for convective drying. Osmotic treatment reduces water activity, provides microbiological stability and extended shelf life of products. In addition, osmotic pre-treatment has a positive effect on the mechanical properties of the final product. The impact of osmotic drying on the change of quince color and volume was examined. Quince cubes of dimensions 15×15×15 mm were used in the experiment. Osmotic drying was carried out with the following combinations of temperature and concentration of sucrose solution in water: 40°C, 50°B×; 60°C, 50°B×; 40°C, 65°Bx and 60°C, 65°Bx. Drying time was 180 minutes. The samples were tested every 20 minutes. The samples, treated by osmotic drying, were air dried convectively at the temperature 40oC for 20 hours. Color measurement was performed by Konica Minolta colorimeter CR-400. CIE L∗a∗b∗ values were used for color parameters. During osmotic drying significant changes in parameter b∗ were measured, while the parameters L∗ and a∗ did not change significantly. At high values of temperature and concentration of osmotic solution less color change occurs after convective drying. The biggest changes in volume were measured again at the highest values of temperature and concentration of osmotic solution.