Optimization of Osmo-Convective Dehydration Process for Dry Tomato Production

Abstract

The aim of this study was to evaluate the sensorial and nutritional quality of dried tomato, obtained by osmotic dehydration and drying, using the experimental design to optimize process conditions. Tomatoes of Ap variety were dehydrated in osmotic solution, prepared with sodium chloride (0–10%) and sucrose (3.96–46%), after being dried at the kiln, at temperatures from 56.6 to 73.4C. A central composite rotational design (CCRD) 23 was used to evaluate the effects of osmotic solution concentration, immersion time and drying temperature under the responses of color and lycopene content parameters. The maximum values of lycopene and chroma, and lower values of hue and brightness were defined by using the optimization method. In drying kinetics, the concentration of the osmotic solution had significant effect on weight loss, with reduction of the drying time. The concentration of the osmotic solution and the drying temperature had a significant effect on color and luminosity parameters. Chroma index and hue angle and osmotic solution concentration had a significant effect in lycopene concentration. The process showed overall desirability of 62.43%, and the levels of the factors were defined in the following condition: the osmotic solution concentration of 15.5%, immersion time of 12.8 min and a drying temperature of 67C. Under these conditions, it was possible to obtain dried tomatoes with luminosity of 31.80, index chroma of 33.20, hue angle of 35.31 and lycopene content of 144.80 µg/g. Practical Applications Dried tomatoes appearance is directly related to the sensorial quality in the evaluation of consumers. The dried tomato is a noble product with exotic flavor and used in different preparations. The use of experimental design to the selection of factors and process' optimization contributes to the preparation of dried tomatoes with less drying time, maximum lycopene content and color intensity.