Shadi POURSAEEDI - M.Sc. Student, mechanization of Agricultural Machinery, Agricultural Machinery Eng. And mechanization Dept., Shahid Chamran University, Ahvaz, I. R.,
Hassan ZAKI DIZAJI - Assistant Professor, Agricultural Machinery Eng. And mechanization Dept., Faculty of Agriculture, Shahid Chamran University, Ahvaz, I. R. Iran
Houshang BAHRAMI - Assistant Professor, Agricultural Machinery Eng. And mechanization Dept., Faculty of Agriculture, Shahid Chamran University, Ahvaz, I. R. Iran

Drying is the oldest method of preserving foods that reduces food moisture content to inhibits the growth of microorganisms. This paper examined the effect of ultrasonic pre-treatment before air-drying on dehydration of tomato tissues and allowed the estimation of water loss and solid gain during the pre-treatment and the effective water diffusivity in the air-drying process. Tomato slices submitted to ultrasonic waves for different times (15, 30, 45, 60, 90 min), then transferred to an Air - Circulating Oven. results showed that the water effective diffusivity increased by 64.33% (best result) after 60 min application of ultrasound, which caused a reduction of about 52.64% in the total drying time .

Tomato; Drying; Ultrasound; Osmotic dehydration