Abstract
For the purpose of monitoring the interior state of ‘Shiitake’ mushrooms during drying, especially for estimating the moisture conditions, electric impedance of the cap was measured in a frequency range of 42Hz to 5MHz and in a moisture range of 133.1% d.b. to 1671% d.b.
Cole-Cole plots showed that the circular-arc shape in the plot-curve characteristic of agricultural products disappeared as drying progressed.
The dependency relationship plots of logarithmic resistance to moisture content were divided into two parts at the turning point; showed linear relationships and the other exponential. A moisture estimating formula at 42 Hz of measuring frequency was proposed and its parameters were calculated by the non-linear curve fitting method. The formula had an estimation error of 10.0% in the higher moisture region of more than 590.2%, d.b. and 17.4% in the areas with a moisture content below that threshold on an average relative error basis.
