Mathematical Modelling the Drying Kinetics of Beetroot Strips during Convective Drying at Different Temperatures

Abstract

The thin layer drying of beetroot strips was evaluated at drying temperatures from 60 °C to 90 °C using convective dryer at inlet air velocity of 1.0 m/s. The different drying models were tested to evaluate the drying characteristics of beetroot strips. The investigations showed that Page’s and modified Page’s equations were satisfactorily describing the drying behaviour of beetroot strips during convective drying with appreciable high correlation coefficient (0.9971<r<0.9990) with low error values. The effective moisture diffusivity was increased from 3.563 x 10-10 m2/s to 8.038 x 10-10 m2/s with increase in drying temperature. The temperature dependency of effective moisture diffusivity was described by Arrhenius equation and activation energy for moisture diffusivity was 30.08 KJ/mol. The drying kinetic coefficients were significantly (p<0.05) affected by drying air temperature. The exponents of models were decreased linearly with drying air temperature during drying of beetroot strips. The equilibrium moisture content was markedly affected by drying air temperature and it decreased linearly with drying air temperature. The results were very useful in standardisation and optimisation of drying process of beetroot strips in large scale commercial production.