Effect of Thymus vulgaris post‐extraction waste and spent coffee grounds on the quality of cultivated Pleurotus eryngii

Abstract

The study demonstrated that Pleurotus eryngii cultivation on substrate enriched with thymus (Thymus vulgaris) post-extraction waste (TPEW) and spent coffee grounds (SCG) can beneficially affect yield and modify the mineral composition, profile of phenolic compounds, organic acids, and antioxidant activity. Cultivation with TPEW and SCG did not result in any significant differences in the contents of K, Mg, P, and S in fruiting bodies. The highest content of Ca and Na was recorded in cultivation with TPEW. The use of TPEW and SCG increased the total phenolic content, while in the phenolic profile changes were observed in the variants of 50% and 100% TPEW and 50% SCG. Cultivation with TPEW increased the sum of the organic acids and quinic, malonic, malic, acetic, and succinic acids, while addition of SCG resulted in their significant decrease. Practical applications The use of different additives to growing substrate is a possible way to improve the harvest yield. Moreover, this modification of cultivation allows to manage some waste materials. However, the application of waste materials can carry the risk to introduce substances potentially dangerous for human health into substrate. Additionally, the supplementation allows to modify the content of bioactive compounds. In this context, the monitoring of the quality of fruiting bodies seems to be necessary. Therefore, the study evaluated the content of elements (especially toxic trace elements), some bioactive compounds and antioxidant activity was examined. The results pointed, how the waste materials added to the substrate affect the quality of the final product. These findings could lead to improvements in the commercial production of P. eryngii and increase the quality of the final product.