Free Amino Acid and ATP-Related Compounds in Sterile Tiger Puffer Fish (Takifugu rubripes ) Fillets Stored at 4C

Abstract

A method for the production of sterile fish fillet was developed to create a raw fish that can be refrigerated for more than 21 days. Immediately after being killed, tiger puffer fish (Takifugu rubripes) were skinned, gutted and filleted using an aseptic method, and the prepared fillets were immersed in boiling water for 10 s after vacuum packing and were rapidly chilled. This processing method left the fish raw inside. Eleven trials of the production on 11 individuals succeeded in the production of 22 sterile fillets. The products showed no bacterial detection even after storage for 21 days at 4C. The contents of inosine 5′-monophosphate (IMP) of the refrigerated sterile fillets remained at ca. 2,200 to 2,400 nmol/g, while IMP of nonsterile fillets became undetectable. The refrigeration increased the levels of glutamic acid and alanine in the sterile fillets. The products can be safely consumed as a sliced raw fish, sashimi. Practical Applications Raw fish, especially sashimi, is a high-priced delicacy in Japan. However, raw fish is highly perishable, and its shelf life is limited to several days after killing. The method developed for preparing sterile fish fillet is applicable to all kind of fish, and meets the demands of the fish industry for fresh products with extended shelf life. The refrigeration of sterile raw fillet can save energy costs that are high in freezing and frozen storage. Sterile tiger puffer fish fillets can be refrigerated for a long time and can be used as a new ingredient in Western food restaurants that previously have not been able to utilize tiger puffer fish. Tiger puffer fish is served only in restaurants specializing in tiger puffer fish since it is very expensive and perishable.