Seaweed Amended Rice Straw Substrate and its Influence on Health Related Nutrients, Trace Elements, Growth and Yield of Edible White Elm Mushroom (Hypsizygus ulmarius)

摘要

Edible mushrooms have been widely used for a long time as a source of food and beneficial health related nutrients. With mushrooms being saprophytic feeders, the nutrient content of edible mushrooms is widely dependent on the substrate composition. This study thus looked at the possibility of improving the quality of rice straw substrate by amending it with seaweeds and its influence on substrate biological efficiency (BE), mushroom (H. ulmarius) health related nutrients and trace metals contents. The results indicated that incorporation of 5% seaweeds resulted in the highest total yield with 22% higher BE than that of the control; whilst incorporation of 10 and 20% seaweeds reduced total yield and BE by 14 and 22%, respectively, compared to the control. Similarly, incorporation of seaweeds at 5% level resulted in significantly the highest crude protein concentration in the mushrooms. However, this high concentration in crude protein did not result in a direct increase in the 9 essential amino acids (EAA) determined in this study, with the control actually having a higher concentration of most of these EAA. Incorporation of seaweeds resulted in higher concentration in trace metals such as Na and K, which are beneficial to human health. Among the heavy metals determined, Cd and As significantly increased under the seaweed amended treatments, though their concentrations were below the maximum permissible levels set for food materials. The results of this study clearly showed that seaweed incorporation into rice straw at 5% level optimized the substrate conditions resulting in the highest mushroom yield, minerals and protein content. Further studies should evaluate the influence of specific seaweeds incorporated into different substrate with several oyster mushroom species on final health related nutrients and heavy metal accumulation.