Drying Kinetics of Mints Tea in Spouted Bed System
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Abstract
Testing data from a spouted bed drier which was designed base on physical properties of mint leaves were collected and analyze for drying kinetics equation. Kinetics equations of drying mint leaves with moisture from 87%wb or 660%db, humidity changes versus time in the temperature range of 40 oC - 45 oC are likely to be a Polynomial Function while in the temperature range of 50 oC. - 55 oC are likely to be Exponential Function, particularly temperature range of 50 oC - 55 oC conform to Logarithmic, Two term and Modified Henderson & Pabis drying model. However, the most appropriate is Two term model, when apply hot air at distribution grid with constant velocity of 0.3233 m/s and temperature of 55 oC, the effective diffusion coefficient of moisture in the 1.038x10-3 - 1.581x10-3 m2/s and activation energy was 65.84 kJ/mole. The color of dried mint leaves due to the temperature of the hot air was increased, the value of L* and b* values were decreased while a* values tend to increase.
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