Single Layer Drying Characteristics of Half Fruit Tomato

Abstract

Drying kinetics of half fruit tomatoes were investigated in a laboratory dryer at the temperature of 35–65°C and air velocity of 0.13–1.00 m/s. The optimum drying conditions in terms of drying rate, colour and growth of microorganisms were also identified. Drying rate and shrinkage increased significantly with the increase in air temperature. But the red colour (a*) decreased significantly with the increase in air temperature. Drying rate increased with the increase of air velocity up to 0.75 m/s. The optimum drying air conditions was the temperature 55°C and air velocity 0.75 m/s, when drying time, colour, ripeness and growth of microorganisms were considered. Microorganisms (molds and fungus) were grown at or below 40°C temperature and it could be prevented by sodium metabisulphite pretreatment. The experimental data were fitted to six different single layer drying models and Midilli-Kucuk-Yapar model was found the best to predict the moisture content.