Intensification of drying process of shiitake mushroom (Lentinula edodes) using combined methods of dehydration

Abstract

This study evaluated kinetics and value of swelling coefficient of cultivated shiitake mushrooms depending on different regimes of combined infrared and convective dehydration methods. Fresh cultivated shiitake mushrooms were sorted by shape, maturity, and size. The kinetics of the process was studied during convective two-stage drying (100 ºС+60 ºС) and combined infrared radiation and convective dehydration (100 W+60 ºС) drying. The drying of shiitake mushrooms at a heat carrier temperature of 60 °C takes 156 min. and using the two-stage convective method at 100/60 °C takes 97 min. When using the combined infrared radiation and convective dehydration method (100 W+60 ºС) the drying process takes 110 min. The use of the combined method (100 W+60 ºС) and two-stage (100 ºС/60 ºС) reduces the duration of drying by 1.4–1.6 times compared to the traditional mode of 60 ºС. The efficiency of these processes is confirmed by a change in the Rebinder number, which depends on the heat carrier temperature and moisture content. During the period of changing the moisture content in shiitake mushrooms from 84 to 10%, the value of the Rebinder number is minimal. When the content of moisture in mushrooms reaches 10%, the Rebinder number increases sharply, which means that most of the energy is spent on heating of the material that leads to an increase in energy consumption for the process and a deterioration in the quality of the drying product. The determination of rehydration properties of mushrooms confirmed the high quality of the dried product.