Salmon fills a prominent place in almost any tray of sushi and sashimi. Its richness, mellow flavor and vivid color make it a favorite with both chefs and diners, so finding high-quality salmon is a priority for most enthusiasts making sashimi at home. Unfortunately, fresh, never-frozen salmon can be hard to find in many areas. Frozen salmon can fill that gap, providing quality and food safety that equals or surpasses fresh-caught salmon.
The Question of Freshness
Part of the mythology that surrounds sushi is the impression that only the most absolutely fresh ingredients are acceptable. That's true up to a point, and occasionally well-connected sushi chefs have the opportunity to work with fish that are alive when they reach the restaurant. More often, especially in inland areas, chefs rely on fish that are shipped on ice from the coast or sold in frozen form. Like other fish, salmon are highly perishable and their quality begins to deteriorate as soon as they're taken from the water. Often, frozen salmon retain their quality better than fresh.
Top-quality salmon, whether wild-caught Pacific or farmed Atlantic fish, are typically processed in two ways. A portion of the catch is sold fresh, shipped on ice in refrigerated trucks. The remainder is blast-frozen at the processing plant immediately after cleaning, or in some cases on the fishing vessel itself. With frozen foods, the speed of the freezing process is the most important factor in ensuring quality. Your home freezer works slowly, creating large, grainy ice crystals in the fish that rupture cell walls and impair its texture. Commercial blast freezing is much quicker, resulting in fine ice crystals and minimal loss of quality. Because the fish is frozen immediately after it's harvested, it thaws to a perfectly fresh condition.
Freezing and Food Safety
A freshly thawed fillet of top-quality frozen salmon can be decidedly better than a days-old "fresh" fillet that's been kept on ice, but that's not the only reason to purchase frozen salmon. Raw fish is a carrier of many parasites and microorganisms that can result in food-borne illness. In many parts of the country it's illegal to serve raw fish -- sushi, sashimi, ceviche and similar preparations -- unless it's first been frozen at very low temperautes, to kill parasites and pathogens.
The rest of the food safety picture is up to you. Begin by thawing the salmon safely, overnight in the refrigerator. That way its temperature remains below 40 degrees Fahrenheit, the threshold for food-safe storage. Scrub your hands, knife and work surfaces thoroughly with hot, soapy water before you cut the salmon, and again afterwards. Don't cut the fish until your remaining ingredients are made up and ready to use. Serve or refrigerate the salmon immediately after cutting it, and discard any that's uneaten after two hours at room temperature.
- On Food and Cooking: The Science and Lore of the Kitchen; Harold McGee
- Fresh and Frozen Seafood -- Selecting and Serving it SafelyU.S. Food and Drug Administration:
- The New York Times: Sushi Fresh From the Deep . . . the Deep Freeze