Fulvic acids-like substances exuded from shiitake mushroom beds—Amount, chemical characteristics, and antioxidant capacity

Abstract

During the cultivation of shiitake mushroom beds (Lentinula edodes), dark colored soluble organic matter that resembles fulvic acids (FAs; alkaline and acid soluble humic substances) are leached. As FAs have multiple functions, such as carriers of trace elements and free radical scavengers in the environment, these substances would be to be functionally similar. This study aimed to evaluate the amounts, chemical characteristics, structural components, and antioxidant capacity of FAs-like substances in leachates from shiitake beds as a biofunctional material for industrial use. The concentrations of FAs-like substances in the leachates ranged from 110 to 854 mg of carbon L−1. That they were structurally similar to soil FAs was confirmed but the aliphaticity and average molecular weight were higher for the FAs-like substances. Higher degree of oxidation of FAs-like substances with shiitake growth was indicated. The antioxidant capacity was greater than or comparable to the soil FA examined in the present study.