Thin-layer Drying Kinetics of Osmotic Dehydration of Cherry Tomato

This paper was aimed to study the thin-layer drying of osmotic dehydration of Thai cherry tomato (Queen cherry tomato) and to investigate the thin-layer drying kinetics of osmotic dehydration of cherry tomato by using a convective air dryer. The osmotic dehydration of cherry tomato was dried under controlled conditions of temperature of 50 degrees C, 60 degrees C and 70 degrees C and relative humidity (rh) of the drying air from 20% to 30% with the airflow rate fixed at 1 m/s. According to the experiment result, the drying rate curve showed that drying process took place only in the falling rate period. Seven different thin-layer models (Newton, Page, Henderson and Pabis, Logarithmic, Wang and Singh, Two-term, Modified Henderson and Pabis) were fitted to the experimental data of osmotic dehydration of cherry tomato. Additionally, diffusivity of osmotic dehydration of cherry tomato was investigated at 50 degrees C, 60 degrees C and 70 degrees C. The drying parameters of osmotic dehydration of cherry tomato were found to be a function of drying air temperature and relative humidity. The Page model was revealed to be the best and it was followed by the Newton models. The agreement between the predicted and experimental values for the Page model is excellent, so that this can be used to provide design data for simulation and optimization of the dryer for efficient operation. The effective moisture diffusivity of osmotic dehydration of cherry tomato increased when the drying temperature increased. The value was in the range of 1.0442 x 10(-10) to 5.1533 x 10(-10) (m(2/)s).