Signs that salmon has spoiled or gone bad include a pungent fishy odor and a slimy texture. While salmon naturally has a slight fish scent, the odor is extremely pronounced and unappetizing when the salmon is bad. Additionally, salmon that has spoiled tends to be slightly off in color.
Storing salmon properly prior to use is essential in keeping the salmon fresh. Canned salmon and freeze-dried salmon are safe when stored in a cool pantry up to its expiration date. Fresh salmon should be refrigerated as soon as possible after purchase. If the fresh salmon packaging has been opened, storing it in an airtight sealed container can help extend the expiration date and keep the salmon fresh.
Freezing salmon is another way to extend its expiration date. It keeps best when stored in a freezer-safe container, as this helps to preserve the overall taste of the fish. Typically, fish fillet producers measure the freshness of fish based on when the fish was caught and the overall color and texture of the fish, as well as by using special bacterial counters. Researchers have recently developed a new measuring instrument that accurately detects how fresh the fish is prior to distribution by using light technology at several different wavelengths.