Fresh salmon can be frozen for future use by following a process of preparing, pretreating, and packaging the fish. Salmon, being a fatty fish, fares better when frozen using a pretreatment including ascorbic acid to prevent flavor change.
Start with salmon that is as fresh as possible. Begin by washing fish thoroughly. If the salmon is whole, descale the fish, remove the head, dorsal fin, entrails and spine. Cut large fish into steaks or fillets for easier preservation and cooking. Once this has been completed, the fillets or steaks need to be pretreated. Salmon is categorized as a "fat fish," and, prior to packaging, should be dipped for 20 seconds in a solution of 2 tablespoons crystalline ascorbic acid and 1 quart cold water.
To package and freeze the salmon, an ice glaze method may be used. Place unwrapped and uncovered pretreated fish in the freezer until just frozen. Remove from the freezer, and dip each piece in near frozen water. Return to the freezer to harden the glaze. Repeat this process until a uniform sheath of ice has formed around the salmon steak or fillet. Wrap the salmon in freezer-safe, moisture-resistant paper and place in freezer bags. Date the bags, and store in the freezer.