Valorization of Pleurotus ostreatus stipes: optimized ergothioneine extraction and multi-omics insights into Agaricus bisporus preservation

Large quantities of Pleurotus ostreatus stipe by-products are generated during mushroom cultivation and processing, yet they are often discarded, leading to resource waste and environmental burden. These residues are rich in ergothioneine, a sulfur-containing antioxidant with strong stability and bioactivity, offering potential for sustainable valorization. In this study, ultrasound-assisted extraction was optimized using response surface methodology with a Box–Behnken design. The optimal conditions (50 °C, 60 W, 61 min, solid–liquid ratio 1:51 g/mL) yielded 3.69 ± 0.07 mg/g ergothioneine, closely matching model predictions. The extract exhibited strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity. When applied to fresh Agaricus bisporus , ergothioneine treatment significantly inhibited browning, reduced weight loss, and maintained firmness during 13 days of cold storage. Biochemical analyses revealed lower malondialdehyde accumulation, higher phenolic and reducing sugar retention, and reduced activities of enzymes associated with browning and softening. Integrated transcriptomic and metabolomic analyses indicate that ergothioneine modulates oxidative stress and phenolic metabolism pathways, providing molecular support for its preservative effects. These findings demonstrate the potential of P. ostreatus stipe by-products as a sustainable source of ergothioneine for natural food preservation, providing a circular-economy approach to mushroom waste valorization.