Sorption isotherms and drying characteristics of mulberry (Morus alba)

Abstract Drying characteristics of Mulberry (M. alba) including sorption isotherms and drying kinetics were investigated. Adsorption and desorption isotherms at 10, 20 and 30 °C and isosteric heats of sorption were determined. At higher water activities, as the temperature was increased, a crossing of the isotherm curves was detected. Some hysteresis effect decreasing with higher temperature was observed. Mulberry was dried in a pilot plant tray drier with a constant air velocity of 1.2 m s −1 at 60, 70 and 80 °C. Only falling rate drying periods (three falling rate periods) were observed in the mulberry drying experiments. The diffusivity values changed from 2.32 × 10 −10 to 2.76 × 10 −9 m 2 s −1 within the given temperature range. Effect of temperature on the diffusivity was expressed by an Arrhenius relation with an activation energy value of 21.2 kJ mol −1 .

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