Analysis of the Drying Characteristics Model of ‘Shiitake’ Mushrooms

Abstract

‘Shiitake’ mushrooms have a considerable moisture content at harvest time and thus their drying is usually accompanied by rapid shrinkage of the surface area. Precise estimation of the surface area, which changes with the drying progressing, can facilitate the determination of the most suitable drying model for ‘Shiitake’ mushrooms.
In this study, two experiments for developing new relationship formula between the surface area and the moisture contents were conducted first. One is for the relationships between the surface area and the volume of drying ‘Shiitake’ mushrooms, which used an image processing technique as a measuring method. The other is for the relationships between their densities and moisture contents which used the liquid substituting method in measuring the densities. Combining these two relationships created a new relationship formula between the surface area and the volume of drying ‘Shiitake’ mushrooms.
Secondly, natural convective drying experiments for ‘Shiitake’ mushrooms were conducted at drying air temperatures of 40, 50 and 60°C. Then, the two drying models obtained from different views of the drying mechanisms were constructed. Comparison of their accuracies in estimating moisture content changes during drying showed that the drying formula based on an apparent constant rate drying model prevailed at all drying temperatures tested.
The newly constructed drying formulae induced in this study would be available not only for developing ‘Shiitake’mushrooms driers but also for application to the drying of other agricultural products with high moisture contents similar to ‘Shiitake’ mushrooms.