Application of ergothioneine-rich extract from an edible mushroom Flammulina velutipes for melanosis prevention in shrimp, Penaeus monodon and Litopenaeus vannamei
This report investigated the melanosis-inhibiting properties of crude water soluble extract from the base and fruiting body waste of an edible mushroom ( Flammulina velutipes ) containing 9.13 ± 2.03 mg/mL 2-thiol- l -histidine-betaine (ergothioneine, ESH). Immersion of live full-grown black tiger shrimp ( Penaeus monodon ) and Pacific white shrimp ( Litopenaeus vannamei ) in a 0.5% w/v solution of mushroom extract for 1 h significantly decreased polyphenoloxidase (PPO) activity in shrimp hemolymph and expression of the prophenoloxidase ( proPO ) gene in hemocytes. Consequently, the development of melanosis in the treated shrimp during ice storage was prevented. Treatment with a 0.05% w/v solution of sodium sulfite and 4-hexyl-1,3-benzenediol had a similar effect. Enzyme assays showed that ESH is a non-competitive inhibitor. It is proposed that ESH possibly interacts directly with Cu 2+ at the putative binding sites of PPO and proPO , based on copper-chelating activity analyses, thus preventing melanosis in the shrimp. This study indicated that application of ESH-rich F. velutipes mushroom extract from trimming waste is an effective natural alternative to synthetic melanosis-inhibiting agents to prevent postmortem melanosis in shrimp. ► Immersion of live shrimps in an EHS-rich mushroom extract inhibited melanosis. ► L-ESH inhibited PPO activity and suppressed pro PO gene expression in shrimp hemocyte. ► L-ESH is a non-competitive inhibitor and has shown copper-chelating activity. ► Mushroom extract has same effect with sulfite and resorcinol on melanosis inhibition.