Packaging for freshness and the prevention of discoloration of fish fillets

Fillets of various kinds of fish are currently packed in thin films (e.g. polyvinyl chloride) for sale at supermarkets; however, these fillets are not necessarily fresh or of good quality. Packed fillets must be certified for safety, freshness and quality, because sensory judgement is difficult. In order to understand how the freshness and colour of red fish meat can be retained, the methods of packaging were examined. It was known that for freshness the packed fillets must be kept at a low temperature, but discoloration of red meat could not be prevented by this alone. However, discoloration of red‐meat fish, such as yellowtail and oceanic bonito, can be prevented by packing with nitrogen gas (N 2 ).