Hot‐Air Drying Characteristics of Soybeans and Influence of Temperature and Velocity on Kinetic Parameters

Abstract

AbstractThe kinetics of the hot‐air drying of soybeans was modeled in order to evaluate the influence of temperature and velocity on the kinetic parameters. A convective dryer with air temperature from 30 to 195C and air flows of 0.75, 1.35, 2.0 and 2.5 m/s was used. Three different mathematical models were applied to simulate the drying process (two empirical equations, exponential and Page's, and Fick's diffusion model) and the diffusivity coefficient increased from 2.5 × 10−11 to 6.69 × 10−10 m2/s for a range of air temperature between 30 and 195C. Both temperature and velocity influenced drying rate. The differential evolution optimization method was used toward parameter estimation. The goodness of fit of the proposed models, evaluated using linear regression coefficient (R2), chi‐squared parameter (χ2) and root mean square error, indicated a satisfactory validation, mainly regarding to the exponential and Page's models.Practical ApplicationsAlthough biological materials are dried to improve shelf life, reduce packaging costs and enhance sensorial aspects, they are highly susceptible to quality deterioration during dehydration if the processing parameters are not well adjusted. The mathematical modeling of food drying provides results about the influence of process parameters on energy efficiency and final product quality in order to help the optimization and upscale application. Given that up to 40% of the agro‐industrial production is lost in developing countries due to the lack of processing and that an energy efficiency improvement of 1% may result in 10% increase in profit, it is important to explore the potential of mathematical tools to properly study drying processes under an energy and qualitative approach.