Kinetics Modeling and Moisture Diffusivity of Onion Slices in Fluidized Bed Drying

Drying characteristics of onion (Allium cepa L.) was studied with different combinations of air temperature (50, 60, 70 and 80C), air velocity (1, 2.5 and 4 m/s) and slice thickness (2, 4 and 6 mm) in a fluidized bed dryer. The drying behavior of onion such as drying rate and moisture diffusivities and their variation with change in drying air parameters were analyzed. Drying took place mainly under falling rate period and drying rate decreased with the moisture content of the samples. It was observed that the drying behavior of onion was better represented by the Page's model as compared with the exponential model. Moisture diffusivity values of onion ranged between 2.148 × 10−9 and 1.474 × 10−7 m2/s for the drying conditions under study. PRACTICAL APPLICATIONS The research results of the article will be useful for the industries involved in onion drying. Further, this article will help the researchers and academicians working in drying of agricultural commodities in general and onion in particular.