This work studies the consequences of neglecting heat transfer effects in the Fick's law solution of food dehydration problems. A semi‐empirical approach is presented which correlates temperature and moisture changes of sugar beet root during the first falling rate period of drying; while the coupled heat and mass transfer equations are not solved rigorously, the approach gives a fairly accurate representation of the experimental results. An improved analysis through Fick's law is possible when the effect of changing sample temperature is considered.

The effect of several variables on the drying rate of sugar beet root slices has been investigated. The standard solution of the nonstationary-state diffusion equation was used to analyse the experimental results during the initial phase of the falling rate period of drying.It was found that Fick's law can be used to predict average drying time, internal moisture distributions and sample temperature during dehydration with reasonable accuracy, despite the complex nature of the mechanisms of moisture transport.

Summary The water sorption isotherms of raw sugar beet root and its water insoluble components, at various temperatures, were determined. An attempt is made to describe the experimental equilibrium moisture content data using some existing theories on physical adsorption.