Preventing discoloration and lipid oxidation in dark muscle of yellowtail by feeding an extract prepared from mushroom (Flammulina velutipes) cultured medium

A hydrophilic extract prepared from waste medium from mushroom (Flammulina velutipes) cultivation contained ergothioneine (ESH) at a concentration of 340 mg/L (= 48 mg/kg of solid medium). The content of ESH in the extract at which 50% of the DPPH radical was scavenged was 0.3 μg. Effects of the extract on color stability and lipid oxidation in dark muscle of yellowtail (Seriola quinqueradiata) during chilled storage for 4 days were evaluated by feeding the extract to the fish as a supplement.There was no mortality during the 4-week feeding period, and the fish grew normally. Browning development in dark muscle of yellowtail fed diets containing 1% and 10% of the extract was remarkably suppressed during 4 days of storage at 0–2 °C. These results clearly showed that the extract is a promising source of natural antioxidants that can be used in aquaculture to improve the quality of fish meat during post-harvest storage at lower temperatures.