How to prepare fish and shellfish
In the preparation of seafood, great care must be taken not to overcook; cooking too long or at too high heat is the most common mistake when preparing fish or shellfish. It results in excessive flakiness, dryness, and flavor loss in fish and toughness in shellfish. For shellfish, however, the “well done rule” should always be observed, especially when microwaving, because of the increased chance of their carrying foodborne illness. Shellfish are often simmered or steamed; the results with dry heat are harder to guarantee, because the meat may dry out and toughen. Nevertheless, with precautions such as breading taken against drying, shrimp, lobster tails, and half-shelled oysters and clams are fairly commonly baked, broiled, or fried. Both temperature and time need to be carefully controlled in either dry- or moist-heat preparation of seafood. The following below refers to the preparation of finfish unless shellfish is specifically mentioned.
Dry-Heat Preparation of Fish and Shellfish
Baking. Fish to be baked should be rinsed, patted dry with paper towels, and placed in a shallow pan. Season as desired, and place in a moderate oven (350° to 400°F/180° to 200°C). Baking time will vary depending on the shape and thickness of the fish, but a general rule of thumb is to bake up to 10 minutes per inch of thickness measured at the thickest diameter of the fish. Basting with butter or covering the fish with vegetables cuts down on moisture loss. Some prefer to prepare whole or drawn fish with the head and tail left on to help keep juices inside. Additional flavor can be added by filling the cavity with herbs and spices. Leaving the skin on whole or drawn fish seals in the moisture and flavor. Moisture loss may also be prevented by wrapping the fish in foil, parchment paper, grape leaves, or leafy greens. These techniques of enclosing the fish technically results in a moist-heat cooking method because the fish steams in its own juices.
Fish is done when it flakes easily with the gentle pressure of a fork without falling apart. The opaque look of fish that has been properly prepared is caused by denatured proteins that unwind and hook together with other proteins so that water can attach, resulting in a whitish hue. The presence of this “white” mesh results in a moist and tender flesh. Heating much beyond this stage tightens the protein bonds, shrinks the protein mesh, and squeezes out the water, resulting in a tough, dry, unappetizing fish flesh. Other signs of doneness include any bone being no longer pink and/or the flesh becoming firm, turning from translucent to opaque, and/or separating from the bone. The flavor, moisture, color, and texture of baked fish are often enhanced by the addition of sauces.
Shellfish are often prepared by baking; examples include lobster thermidor, baked soft-shell clams, and oysters Rockefeller. In lobster thermidor, the lobster is split in half and baked. The meat is then extracted and mixed with a seasoned bechamel sauce before being put back in the lobster shell and baked again until golden brown and heated through. If soft-shell clams are to be baked in the oven, they are placed in a pan layered with rock salt and baked at 425°F (218°C) oven for about 15 minutes or until the shells open. Oysters Rockefeller is made by pouring a spinach mixture over half-shell oysters in a pan layered with rock salt. They are baked at 475°F (246°C) for about 10 minutes and then browned briefly under the broiler.
Broiling. Dressed or filleted finfish or fish steaks are best broiled at 5 inches or less below the heat source. Lean fish should be coated with melted butter, margarine, or oil, but this step can be omitted with most fatty fish. Season the fish as desired, and place it skin-side down on a pan that has been greased to avoid sticking and broil it on one side until tender. Lobsters and large shrimp can also be broiled. Whole lobsters need to be killed and split before broiling, while lobster tails can be broiled whole.
Grilling. Fish can be grilled on an outside grill or in the oven. Grilling is not recommended for delicate fish such as sole, because they may stick to the grill and fall apart easily. Fatty, firm-fleshed fish such as salmon, bluefish, and mackerel that have been drawn or cut into steaks are well suited for grilling. Also, larger shrimp may be put on skewers like kabobs and grilled. A fat coating such as oil or even mayonnaise can be applied to the fish to prevent it from sticking to the grill. The grill itself should be scraped of any residue and lightly oiled to prevent sticking. Steaks are seasoned as desired, and cooked on both sides if thick, but on only one side for thin steaks or fillets. The fish should be about 4 inches from the heat source. When the fish flakes easily, serve it immediately. Drawn fish can be checked for doneness by slipping the tip of a paring knife into the back of the fish and pulling away. It is done if it clings briefly before giving way, but is overdone and dry if cooked to the “flakes easily” stage.
Frying. Lean fish less than 1/2 inch thick, shrimp, and scallops will sauté nicely in a small amount of butter and/or oil. The fish is seasoned as desired and sautéed over medium heat until it is cooked about three-quarters of the way through, at which time it is turned gently with a spatula and heated until the flesh flakes easily. Shellfish are best sautéed on high heat for a short time. Shrimp and scallops are ideal for this type of preparation. When done, scallops will be firm and look opaque, and shrimp will be opaque and pink.
Sautéed fish may be prepared a la meuniere (a-lah-muhn-YAIR). The dish can be served amandine (with almonds), florentine (with spinach), or a la belle (with mushrooms). A variation of this method, but using more fat, is used to prepare trout and other small fish. They are seasoned, breaded or dipped in cornmeal or flour, and pan-fried until they are golden brown on both sides.
Deep-fat frying is a popular method for preparing battered or breaded lean fish and shellfish (shrimp, scallops, clams, and oysters). Whole small fish, shellfish (which must first be shelled), fish fillets, or steaks are dipped in batter or seasoned breading mix before being deep fried in oil until golden brown. The oil is heated to 350°F (180°C) for large fish and around 180°F (82°C) for small seafood such as fish strips, oysters, or clams (25). Fish is always fried alone because it imparts a fishy taste to the oil, which would be picked up by other foods fried in the same oil. Lean fish are preferred because unpleasant oily tastes often occur in fatty fish that are deep fried.