Effects of ergothioneine-rich mushroom extracts on lipid oxidation and discoloration in salmon muscle stored at low temperatures

•Mushroom extract (ME) supplementation had no adverse effect on fish during culture.•Ergothioneine from ME was effectively taken up by the fish.•Addition of ME controlled hydroperoxide accumulation in fish muscle during storage.•Addition of ME mitigated astaxanthin degradation in fish muscle during storage.•Ergothioneine-rich ME improved physical and nutritive quality of fish. The effects of supplementing ergothioneine-rich mushroom extracts (ME) on discoloration and lipid oxidation in astaxanthin-pigmented salmon muscles were evaluated. ME (Flammulina velutipes) were added (in vitro) to minced Oncorhynchus mykiss muscles and stored at −10°C. During several weeks of storage, the ME-treated group showed lower lipid hydroperoxide (HPO) accumulation and higher retained astaxanthin levels than in the control group. The effects of adding concentrated ME (Pleurotus cornucopiae) to Oncorhynchus kisutch diets were also tested over a 2-month feeding trial. No adverse effects on fish growth or pigmentation were observed. Muscle samples were collected, stored (−2 or −18°C), and evaluated. At the end of the storage period, the ME-treated group had lower HPO and higher retained astaxanthin levels in the muscle samples than the levels in the control group. Thus, the addition of ergothioneine from MEs successfully controlled lipid oxidation and stabilized astaxanthin during post-harvest storage at low temperatures.