Analysis of the electrical impedance of tea leaves during the primary drying process
2006
Mizukami, Y.(National Inst. of Vegetable and Tea Science, Shimada, Shizuoka (Japan)) | Miyama, D. | Sawai, Y. | Yamaguchi, Y.
Frequency-dependent electrical impedance spectroscopy was used to characterize the intracellular and extracellular resistances, as well as the capacitance of the cell wall and cell membranes, of tea leaves during the primary drying process. At the beginning of the process, the extracellular resistance significantly decreased due to the leakage of electrolytes into the intracellular space as a result of pressurization by the spatula. When the drying process was prolonged, the extracellular resistance increased due to evaporation from the surface area of the tea leaves and the intracellular resistance also increased due to the decrease in the moisture content of the tea leaves. The capacitance of the cell wall and cell membranes decreased, with the assumptions that the temperature of the tea leaves had a negligible effect on the change in the capacitance and the cellular tissues were physical damaged. The deterioration and collapse of cellular tissues by pressurization was regarded as the main factor contributing to the decrease in the capacitance. These electrical behaviors observed in the primary drying process were affected by the material characteristics.
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