Osmo-mechanical drying kinetics of ber

Investigations were carried out to study the effect of different parameters, viz. drying air temperature, chemical treatment, pricking, stage of harvesting and osmosis on drying kinetics of Indian jujube (cv. Umran). The fruits were dried in the mechanical drier at three different temperatures to a final moisture content of 16%(wb). It was observed that drying air temperature, chemical treatment, pricking and maturity stage resulted in reduction in drying time. Experimental data were fitted to Page's and generalised exponential model. The Page's model fits better with experimental data for its better values of R² compared to generalised exponential model. The drying rate constant k increased with drying air temperature. The results indicated that the Arrhenius law may be applicable to relate the dependence of rate constant on drying air temperature. Activation energies (E) and frequency factor values (ko) were higher in treated and pricked osmo-mechanically dehydrated, Stage II samples compared to others. Higher E values signified greater temperature sensitiveness of these samples. This was reflected in reduced drying times for these treatments. Variation of coefficient ‘n’ with temperature was non-systematic.