Selected nutritional properties of Ganoderma lucidum and substrate degradation during multi-cycle reuse with hazelnut branch waste.

Abstract

In this study, the effects of reusing spent Reishi (Ganoderma lucidum) (Curtis) P. Karst mushroom substrate (SMS) from cultivation-by mixing it with hazelnut branch-based substrate (HB) at different ratios (HB100%, HB75%:SMS25%, HB50%:SMS50%, HB25%:SMS75%, SMS100%)-on the yield, quality, and nutritional composition of mushrooms were investigated. Yield performance, ash contents, and mineral composition of the harvested mushrooms were evaluated. In addition, Total Organic Carbon (TOC), Total Organic Matter (TOM), Nitrogen (N), C/N and Ash contents of the substrates used were determined. Fourier Transform Infrared Spectroscopy (FT-IR) and Thermogravimetric Analysis (TGA) were also conducted to assess structural and thermal changes in the substrates during successive cultivation cycles. Results indicated that the highest biological efficiency (8.32%) and total yield (37.5 g/kg substrate) were observed in the SMS100% and SMS25%:HB75% substrates, respectively. A 29.9% increase in yield was observed when comparing 100% SMS with 100% HB. Mineral contents in mushrooms produced with SMS 100% generally increased compared to HB 100%, except for Cu. A 23.03% decrease was observed in the Cu content when the substrate was changed from 100% HB to 100% SMS. The total phenolic contents of the mushrooms cultivated were found to differ significantly among the substrates. FTIR analysis confirmed structural changes in the substrates, particularly indicating partial hemicellulose degradation and relative lignin enrichment after mushroom cultivation. TGA results showed that spent Ganoderma lucidum substrates exhibited higher thermal stability than raw hazelnut branch substrate (HB), supporting their reuse potential in circular bio-based applications. This study clearly showed that spent Ganoderma lucidum substrate-based HB can be successfully reutilized in new cultivation cycles, offering an economically and environmentally sustainable approach for mushroom production systems.