Quick-cooking, healthful, and delicious, fish is a perfect choice for dinner. here’s what you need to know to cook it best.
When it comes to cooking fish, we face a long list of choices. Wild or farmed? Fresh or frozen? Whole or fillets? And that’s just at the fish counter. At home, more questions arise. Broil or poach? Is it done yet? Understanding a little about fish from a scientific perspective can help answer these questions-read on and learn how to cook any type of fish with confidence.
Should I buy fresh or frozen fish?
Fresh usually wins, but fish is so perishable that frozen fish can be superior to fresh fish that has taken days to reach the market.
The quality of frozen fish largely depends on how it’s frozen. Fish is about 70 percent water, and the longer it takes for that water to freeze, the larger the ice crystals become, eventually piercing and bursting cells in the flesh. When slowly frozen fish is thawed and cooked, the cell damage may cause moisture loss, shrinkage, and dryness in the flesh. The best frozen fish is flash-frozen at sea (often labeled “FAS”) at an average temperature of –40°F to reach a –10°F core temperature in less than five hours. This process kills parasites, minimizes shrinkage, and preserves moisture when the fish is thawed and cooked.
Fish with dense, fatty flesh, such as king salmon, tends to freeze better than fish with lean, delicate flesh, such as haddock. Plus, lean fish in the gadoid family (including haddock, whiting, pollock, and cod) are particularly high in trimethylamine oxide (TMAO), a chemical compound that breaks down to malodorous dimethylamine and formaldehyde; this means that when these fish are frozen and thawed, they’re more likely to develop “fishy” ammonia and sulfur aromas. Frozen and thawed gadoid fish can also suffer from “freeze denaturation,” in which the proteins begin to break down during freezing, creating a dry, spongy texture upon thawing.
If you’re not sure what cooking method best suits your fish, follow these rules of thumb: Lean fish generally benefit from wet-cooking methods, such as poaching and steaming. Fatty fish can stand up to dry-cooking methods like sautéing, grilling, broiling, roasting, and baking. Moderately fatty fish can be wet- or dry-cooked.
|LEAN FISH (0%-3%)||
|FATTY FISH (10% +)|
The fastest, safest way to thaw any frozen fish is inside a sealed bag submerged in ice water. You can also thaw fish in the refrigerator; it will just take longer, since air isn’t as efficient at transferring heat as water. If you’re short on time, you can cook frozen fish without thawing it, a technique that can help create a browned crust while keeping the interior from overcooking. Simply rinse the fish under cold water to remove any ice, and pat it dry with paper towels before cooking.
Is it better to cook fish whole or filleted? Skin on or skin off?
It’s best to cook fish as whole as possible. Fish flesh is low in collagen-the protein that gives cooked meat its rich mouth-feel-but its bones and skin are loaded with it. When fish is cooked on the bone and/or with its skin, the collagen melts, coating and lubricating the lean flesh. Also, because bone is a poor conductor of heat, fish cooked on the bone has less chance of overcooking than boneless fish, and as an added advantage, the skin protects against moisture loss.
What cooking methods are best for lean and fatty fish?
Because of their low fat content (as low as 0.5percent in cod and other white-fresh fish), lean fish can easily overcook from dry-heat methods like sautéing, baking, broiling, and grilling. These fish are better suited to poaching or steaming, techniques that protect with added moisture. If you want to grill or pan-fry lean fish, it’s best to keep them whole. Not only will the bones slow heat transference, but keeping a fish on its skeleton helps the cooked fresh keep its shape.
Fatty fish, such as mackerel, herring, and bluefish, are a better fit for dry-heat cooking methods; they also tend to be higher in collagen, which helps them stay moist. In fact, most fatty fish don’t take well to poaching, which encourages their oils to oxidize easily, yielding off flavors. Salmon is an exception; its fresh contains astaxanthin, a pink pigment accumulated from a diet of ocean crustaceans (or, in the case of farmed salmon, food pellets that contain astaxanthin). When heated with dry or moist heat, this pigment produces aromatic molecules similar to those in fruits and flowers.
Do farmed and wild fish cook differently?
Broadly speaking, wild fish tend to cook quicker than their farmed counterparts. Wild fish swim-and eat-far and wide, developing strong bones and rm, complex fresh. Farmed fish are con ned, so they tend to be fattier than wild fish and to have so er, milder-tasting fresh (wild salmon that are caught soon a er they’ve built up their fat reserves for spawning are an exception). Fat conducts heat more slowly than protein, so fattier fish cook more slowly than lean fish.
To avoid overcooking fish, use a thermometer: 125°F is medium rare, 130°F is medium, 140°F is medium well, and 150°F is well done. Dense-fresh fish like tuna and salmon can be delicious cooked to medium rare (or even raw, as in sushi), whereas delicate-fresh fish like cod and sea bass often taste best medium to medium well. Be sure to avoid holding fish at temperatures between 130°F and 140°F for long; in that temperature range, protein-digesting enzymes remain active and make fish unpleasantly mushy, particularly in species such as herring, mackerel, pollack, sardines, tilapia, tuna, and whiting.
What’s the white substance that sometimes seeps from cooked fish?
It’s albumin, a protein in muscle tissue that coagulates when heated, resulting in an unsightly white substance on cooked fish. Albumin exists in all meat; it’s the same stu that oozes out of hamburgers during cooking, forming gray blobs. (Albumin shouldn’t be confused with albumen [with an “e”], which is egg white, a different substance.) Albumin coagulation happens regardless of the cooking method. However, you can eliminate it by soaking fish in a 10percent salt brine (1-1/4 tablespoons kosher salt per cup of water) for about 20 minutes before cooking; this sets the albumin. (Brining also seasons the fish, so you probably won’t need to add any more salt during cooking.)
How do I get crisp skin on my fish?
Get rid of as much moisture as possible, since moisture in and on the fish skin will interfere with browning and crisping. As you now know, fish skin is rich in the protein collagen, which, when moistened, turns into gelatin. Therefore, moist heat plus fish skin equals a gelatinous sheet. (This is less of an issue with lean fish, whose skin is filmy and contains far less collagen than the skin of fattier fish.) To remove moisture from the skin, let fish fillets sit uncovered on a plate, skin side up, for about an hour in the refrigerator before cooking. Put whole fish on a rack set over a baking sheet to let air circulate on all sides. Salting the skin before air-drying helps dry the skin even further. During cooking, use high heat to evaporate any remaining moisture, and avoid adding lemon juice, wine, or other liquids.