The shellfish family is divided into two basic categories: crustaceans and mollusks. Crustaceans have elongated bodies and jointed shells. These include crab, lobster, and shrimp. Mollusks are divided into three groups:
Gastropods (or univalves) — These have a single shell and single muscle. An example is the abalone.
Bivalves — Like the clam and oyster, bivalves have two shells hinged together by a strong muscle.
Cephalopods — Examples include the octopus and the squid, which have tentacles and ink sacs.
Nutrition
Like fish, shellfish are rich in protein yet low in fat and calories. Compared with other types of meat, however, the amount of cholesterol in most shellfish is about equivalent to that of a lean piece of beef or a chicken breast with the skin removed. Shrimp, squid, and crayfish, however, are very high in cholesterol. They have about twice as much as lean beef, making them something to savor on occasion.
Selection
When selecting shellfish, remember that fresh is best. The best way to guarantee freshness is to buy live. If your geographic location limits your opportunities for live shellfish, check out the freezer case for quick-frozen items, which can be almost as good.
Just as in picking out fish, use your nose to select shellfish. Shucked oysters and clams should be plump and free of any sour aroma. Fresh scallops should have a slightly sweet aroma and, when packaged, be practically free of liquid. Fresh shrimp are firm and have a mild, faintly sweet smell. Crab or lobster should move and not have any noticeable odor.
Next, view the shellfish’s appearance. The liquid packed with oysters should be clear, not pink or opaque. Scallops, lobster, and shrimp flesh should be free of any black spots. When you buy frozen shrimp, crab, or lobster tail, make sure any exposed meat is white, not yellow, and not dried out.
Storage
Once you leave the market, it is important to keep shellfish cool and refrigerate it as soon as possible. At home, shellfish should be rinsed under cool, running water, placed in a container, and covered with wet paper towels. Use shellfish the day of purchase, if possible, or the next day.
Do not seal live oysters, clams, or mussels in a plastic bag. They need to breathe, so store them covered with wet paper towels. Use them as soon as possible after purchase. Shucked oysters that are refrigerated in the original container should stay fresh for a week. Plan to use commercially packaged frozen seafood stored in your freezer within 2 months for best flavor.
Fish and Shellfish Allergies
Seafood is a common source of food allergies. About 250,000 Americans experience allergic reactions to fish and shellfish each year.
People with seafood allergies can have symptoms that range from mild to life-threatening. Even tiny amounts of fish substances can trigger a reaction in some people. What’s more, these allergies are rarely outgrown.
Examples of shellfish that are common causes of allergic reactions include shrimp, crab, lobster, oyster, clam, scallop, mussel, and squid. Fish that can trigger allergic reactions include cod, salmon, trout, herring, sardine, bass, tuna, and orange roughy.
Symptoms of an allergic reaction include nasal congestion, hives, itching, swelling, wheezing or shortness of breath, nausea, upset stomach, cramps, heartburn, gas or diarrhea, light-headedness, or fainting.
If you suspect that you have any food allergies, see an allergist for a careful evaluation. This generally includes a medical history, physical examination, and skin or blood testing. If you are found to have a fish or shellfish allergy, the best advice is to avoid fish or shellfish altogether. That may be harder than it sounds. You may not be aware that seafood is an ingredient in a dish that you are eating. Be sure to check the labels of any product you buy. In addition, make sure that persons close to you are aware of the potential for this kind of allergic reaction. Many people with a food allergy wear medical alert bracelets.
Safety Issues
Persons who eat shellfish raw should beware. Raw shellfish may contain the organisms that cause hepatitis and other diseases. Cooking will kill any microorganisms in shellfish. In addition, because shellfish filter large amounts of water each day, they may contain residual amounts of any pollutants in the water near them. Concerns about potentially harmful chemicals are also a concern about shellfish. Women who are pregnant or thinking about having a child should check with their physician about how much shellfish they should eat.
Another important safety note is that shellfish are a common trigger of allergic reactions in some people (see sidebar: Fish and Shellfish Allergies, page 317).
Abalone
Abalone is actually a large snail that lives in the sea. It has a single shell and a tough, muscular "foot" with which it clings tenaciously to rocks as it grazes on seaweed. The edible portion is this foot.
Abalone is found primarily along the coastlines of California, Mexico, and Japan. Four of California’s seven species constitute most of the commercial catch. From largest to smallest are red, pink, green, and black abalone, with red reaching a legal market size at 7 3/4 inches and black at 5 3/4 inches. Black abalone is the most affordable wild species today. Its meat is tougher and requires more pounding than the other species, but it has an excellent sweet flavor. It is an excellent source of protein and a good source of iron, magnesium, and phosphorus.
Abalone is known by many names: "ormer" in the English Channel, "awabi" in Japan, "muttonfish" in Australia, and "paua" in New Zealand. Its iridescent shell is a source of mother-of-pearl.
Preparation
Like all fresh shellfish, abalone should be alive when purchased — it will move when it is touched — and smell sweet, not fishy. Choose those that are relatively small for best flavor. Refrigerate abalone immediately and cook within a day. Abalone is also sold canned (once opened, refrigerate, covered with water in a sealed container, for up to 5 days), dried (store tightly wrapped in a cool, dry place indefinitely), and frozen (store for up to 3 months).
Widely used in Chinese and Japanese cooking, abalone must be washed first to remove sand that may be caught in the flesh. Abalone must be pounded before cooking to make it tender, because the edible portion is a muscle. Use a mallet to flatten the meat to 1/8- to 1/4-inch thickness. Overcooking abalone can toughen it. Saute abalone briefly, for not more than 20 to 30 seconds per side. Prevent abalone from curling during cooking by scoring the meat at 1/2-inch intervals with a sharp knife.
Serving Suggestions
Abalone is an excellent addition to appetizers and salads. Tough or overcooked abalone can be added to chowders or soups.
Clam
Clams are double-hinged mollusks that fall into two broad categories — hard shell and soft shell. The parts eaten are the muscles clams use to close their shells, although the siphon (the valve used to intake water) and the foot (which nudges this creature along on the ocean’s floor) are also edible. Clams generally are chewy and have a mild, even sweet, flavor. Taste and characteristics vary by the type of clam and its size. All are a lean seafood choice and an excellent source of vitamin Bj2 and iron.
The quahog (pronounced CO-hog) is a hard-shell species from the East Coast and is the largest of Eastern clams (1 1/2 to 6 inches across). Quahog is also a family name for hard-shell clams that can include cherrystones (less than 3 inches) and lit-tlenecks (2 to 2 1/2 inches). Also popular in the East are soft-shell clams called steamers. As the name indicates, they are great for steaming. On the West Coast, soft-shell Pacific geoducks (pronounced GOOey-ducks) weigh between 2 and 4 pounds, although they can be 3 feet long and up to 5 pounds. They have an enormous siphon that extends from the shell; this is often sliced for sushi because it is also quite sweet.
As with all filter feeders, clams sometimes ingest toxic levels of planktonic microorganisms during a condition called red tide and also can become contaminated from pollution.
Cherrystone clams. American Indians called them "quahog."
When buying hard-shell clams such as the littleneck or cherrystone (other varieties include chowder, pismo, or butter clams), make sure the shells are tightly closed. If a shell is slightly open, tap it lightly. If it does not snap shut, the clam is dead and should be discarded. The shells should be whole, not broken or cracked. To test a soft-shell clam, such as geoducks or steamers (another popular variety is razor clams), lightly touch the neck; if it moves, it is alive.
Store live clams in an open container covered with a moist cloth for up to 2 days in the refrigerator. Shucked clams should be plump and the liquor (liquid) surrounding them clear. Store shucked clams in their liquor in the refrigerator for up to 3 days and in the freezer for up to 3 months. If there is not enough liquor to cover the shucked clams, make your own by dissolving 1/2 teaspoon salt in 1 cup water.
Preparation Tips
Get rid of sand by soaking live clams in cold, salted water (use 1/3 cup salt per gallon water) for an hour. Sand also can be removed by covering the clams with water, then sprinkling liberally with corn-meal and letting stand for about 3 hours. Any clams that are floating after these two methods should be discarded.
Live clams should be well scrubbed under cold, running water. Clams are much easier to open if they are put into the freezer in a single layer for 30 to 45 minutes. A quicker method for relaxing clams so that they are easier to open is to drop a few at a time into boiling water. Retrieve with a slotted spoon after 15 seconds and open. Clams also can be microwaved until they open.
Crab, lobster, and the tiny crayfish are all excellent steamed.
Crab, lobster, and the tiny crayfish are all excellent steamed.
Serving Suggestions
Clams should be cooked at low heat to prevent toughening. Clams cooked in their shells are done just when their shells open. Soft-shell clams are best for this method. Use only fresh or frozen clams for soups and stews, because the texture of canned clams is too soft for long-cooking dishes. Clams are often added to soups and stews. A famous dish in which they are featured is clam chowder. When adding clams to this type of dish, do so at the last minute so they do not lose their texture. Clams are also excellent additions to dips, salads, and quiches.
Crab
There are dozens of different crabs on the market today, varying widely in size and shape. Therefore, it is important to know what kind of crab you are buying before bringing it home.
Crabs have 10 legs, the front 2 of which have pincers. There are freshwater and saltwater crabs. Saltwater crabs are the most plentiful. Soft-shell crabs are not a distinct variety of crabs. Rather, they are crabs that have shed their hard outer shell. Before growing a new shell, these crabs (usually a variety called blue crabs) have a 6-hour window during which they have a soft shell. This window can be extended if the crustaceans are removed from water. The benefit of a soft-shell crab is that it can be eaten whole without bothering with a pesky, rigid exterior. Alaskan king crab is another term crab buyers may encounter. Meat from this large crab species is frozen soon after the catch. Then, the sweet, meaty flesh is frozen so it can be shipped to far-flung locations.
Crab is a lean source of protein and an excellent source of vitamin B12.
Preparation Tips
Crab is sold whole, cooked or alive. Choose live crabs that are active and heavy for their size. Hard-shell varieties should not have softening shells. Refrigerate live crabs covered with a damp towel until just before cooking. Live crabs should be used the day they are purchased.
Cooked whole crabs and crabmeat should have a fresh, sweet smell. Cooked crab is available in whole pieces (lump white meat from the body) or in smaller pieces (flaked light and dark meat from the body and legs).
For ease of use, consider using canned crabmeat. Or, if you prefer, choose pasteurized crabmeat, which has been heated in cans but has not been subjected to the higher temperatures of the canning process. For this reason, pasteurized crabmeat should be stored unopened in the refrigerator no longer than 6 months. Use it quickly after opening. Always use your fingers to pick over crabmeat, fresh or canned, to make sure there are not tiny pieces of hidden shell. Refrigerate leftover cooked crabmeat, tightly covered, for not more than 2 days.
Serving Suggestions
Crabmeat has a tender, flaky texture and a delicate, sweet flavor. For the best possible flavor, choose live crabs. If only cooked crab is available, add it to hot dishes during the last minutes of cooking and cook just until hot.
Crabs can be cooked in a variety of low-fat ways, including steaming and broiling or in broth-based soups and gumbos. Crab cakes, traditionally held together with mayonnaise and bread crumbs, are leaving the confines of New England for the rest of the states. A lower-fat version uses egg whites in place of mayonnaise. Instead of floating crabs in a pan filled with oil, try dusting them with flour and reducing the amount of oil you use.
Lobster
One of the largest crustaceans, lobster has a jointed body and limbs covered with a hard shell. The coveted edible portion of the lobster is generally the sweet flesh inside its tail, and sometimes in its claws. Its liver (tomalley) and eggs (coral) also can be eaten. Lobsters are prized by diners for their firm flesh and flavorful, yet not overpowering, taste.
Lobsters can be divided into two groups: large, clawed (American) lobsters and spiny (rock) lobsters. American lobsters hail from around Maine, whereas rock lobsters can be caught in the waters off the southeastern United States and in the Pacific. American lobsters boast claws with yet more meat, but only the tails of spiny lobsters are eaten. These tails are often sold frozen throughout the United States. The meat is more dense and fibrous than that of the American lobster. It lacks some of that characteristic sweetness, but the tails are far more inexpensive than buying a whole American lobster.
Lobster is an excellent source of zinc.
Preparation Tips
When selecting a live lobster, look for an active one whose tail curls under its body when lifted. If lobsters have been stored on ice, they may be sluggish. Bacteria form quickly in a dead lobster, so it is important that you purchase it live. Live lobsters will die quickly, so they must be kept in sea-water, wrapped in a wet cloth, or wrapped in several sheets of wet newspapers. Use these methods for only a few hours (24 hours at most), then cook the lobster. It is best to cook lobster the same day you buy it.
Whole, cooked lobsters should have their tails curled tightly under their bodies, a sign they were alive when cooked. Cooked lobster meat should be sweet-smelling and snow-white. Frozen tails should be in an untorn package with no sign of frost; the visible meat should be free of dry-looking spots.
Lobsters can be prepared in a variety of ways, including steaming, broiling, and grilling. Another common preparation method is boiling. A general rule for cooking lobster with any method is to allow 12 minutes per pound. The lobster is done as soon as its shell becomes red or the meat turns opaque. A sign that a lobster has been overcooked is that its meat is stringy and tough.
Serving Suggestions
The firm flesh and pleasant flavor of lobster make it a versatile seafood. It can be eaten plain, seasoned with lemon juice, garlic, and a drizzle of butter, or added to pates, salads, or sauces. Lobster bisque, essentially a cream-based lobster stew, is a classic lobster dish enjoyed by diners the world over. Because it is high in calories and fat, it should be savored on special occasions. Lobster meat also can be mixed with curry sauce. It is also an elegant, tasteful addition when added to salad greens and sprinkled with lemon juice or a spicy lower-fat vinaigrette.
Mussels
Perhaps it is the dark shell that accounts for its foreboding reputation. Perhaps it is the name, which makes it sound too much like a stringy, tough muscle. Whatever the case, mussels do not have the audience in the United States that other forms of seafood do, even though people throughout the world have been eating them for more than 20,000 years.
Although there are dozens of mussel species, only two reach American markets with any regularity. The blue mussel (which is actually dark blue to black) and the blue-green mussel can be used in recipes interchangeably, but the blue-green type from New Zealand is larger and more expensive. The blue mussel is most abundant, found along the Mediterranean, Atlantic, and Pacific coasts. It is usually 2 to 3 inches in length.
Many mussels are being cultivated instead of harvested because of the dangers posed by microscopic organisms (of red tide notoriety) that make mussels unsafe to eat during the spring and summer months.
When choosing mussels, make sure they are still alive by tapping on their shells. If they slam shut, they are still alive. Those with tightly closed shells also are a good choice. In general, smaller mussels are more tender. Cultivated mussels are usually smaller, and they also lack some of the sand and grit of harvested mussels. Choose shucked mussels that are plump and have a clear liquor (liquid). Or, opt for plain and smoked mussels packed in oil.
Store live mussels in a single layer on a tray in the refrigerator covered only with a damp towel or wet newspapers for up to 2 days. Store shucked mussels in the refrigerator up to 3 days. They should be covered completely with their liquor (liquid). If you need more liquor, combine 1 cup water with 1/2 teaspoon salt and pour this brine over the mussels to cover.
Preparation Tips
Before cooking, use a stiff brush to scrub mussels under cold, running water. Pull out the dark threads (beard) that protrude from the shell. Mussels die when debeard-ed, the term given for removal of these threads, so do not remove the dark threads until just before cooking. Get rid of sand by soaking mussels in cold, salted water (use 1/3 cup salt per gallon of water) for 1 hour. Like all shellfish, mussels should be cooked gently to prevent toughening. Mussels cooked in their shells are done when their shells pop open. Discard any with unopened shells.
Serving Suggestions
An elegant way to serve them is simple: boil them. Add garlic, onion, a splash of olive oil, and white wine to the water while cooking — generally, about 8 to 10 minutes. Saffron also provides an excellent flavor. Serve with French bread. This can be broken into pieces to be used to soak up the flavorful broth you created while cooking the mussels. A general rule: about 1 pound of mussels per person is needed.
Octopus
Although popular in Japan and Mediterranean countries, the octopus in North America is more likely to be a villain of "scary" movies than the star of a seafood meal. But octopus is relatively inexpensive and versatile, and it provides highly flavorful, meaty (albeit sometimes chewy) chunks. Most octopuses weigh only about 3 pounds and reach a size of only 1 to 2 feet before being caught for food.
Fresh octopus already dressed and ready for dishes can be found in many supermarkets and specialty fish markets. Frozen, smoked, and canned octopus is also available. Shop for octopus the same way you shop for fish, using your nose as a guide. Octopus should smell fresh, not fishy, and if it has eyes, they should be bright, not cloudy. As with most aquatic species, octupus that is smaller is younger and more tender. Both the body and all of the tentacles are edible. The ink sac contains an edible black liquid that can be used to color and flavor foods such as pasta, soups, and stews.
Preparation Tips
Always rinse octopus well before cooking. Although many cooks believe that an octopus must be tenderized before cooking (such as by beating it with a mallet or even hurling it against a hard surface), octopus can simply be cooked until it is tender. Cooking time varies by size. Generally, an octopus that weighs more than 4 pounds should simmer for about 45 minutes. This seafood can be cooked in a variety of ways, including grilling, frying, steaming, and poaching.
Serving Suggestions
Octopus is an excellent addition to seafood stews and soups, adding an unusual texture to the dish. Its flavor is enhanced by garlic, tomatoes, red wine, and soy sauce.
Oysters
Oysters have many different names, which are clues to where they come from and their varied taste and appearance. The marine plants they feed on account for these differences. The hard, rough, gray shell contains meat that can vary in color from creamy beige to pale gray, in flavor from salty to bland, and in texture from tender to firm.
Oysters are rich in zinc, iron, copper, and vitamin B12. Interestingly, it is oysters’ relatively high zinc content that gave them their reputation as an aphrodisiac when eaten raw.
Purchase the freshest oysters you can find. Gauge freshness by tapping on the oyster shells with your fingernail. If they snap shut quickly or are already shut tightly, they are fresh. In general, smaller oysters will be more tender than larger ones. Buy shucked oysters of uniform size and color encased in a clear liquor (liquid).
You may store oysters for up to 3 days in the refrigerator using the same method as for mussels, but the sooner you use them, the better. If any shells open during storage, tap them. If they do not close, throw them out. Store shucked oysters, covered by their liquor, for up to 2 days in the refrigerator and up to 3 months in the freezer. If there is not enough liquor to cover the shucked oysters, make your own by dissolving 1/2 teaspoon of salt in 1 cup of water.
Preparation Tips
Scrub live oysters under cold, running water before opening. Oyster knives specially designed for removing the flesh from the shells — which can be a tricky operation — are available at cooking supply stores. Oysters and other bivalves will open more easily if they are heated briefly — such as by steaming them for several seconds or microwav-ing them for a minute.
Serving Suggestions
When fresh and safely available, raw oysters are a unique treat. "Raw bars" serve the traditional "shooter," a New Orleans-inspired hot sauce covering a raw oyster. If you serve them raw, keep them chilled (and prevent the growth of microorganisms) by putting them on a bed of ice.
Oysters in the shell also can be cooked in numerous ways: baked, steamed, or grilled. Oysters Rockefeller, a hot hors d’oeuvre that is baked and broiled with a spinach topping, is a traditional, elegant favorite. Use shucked oysters in dressings or poultry stuffings. Oyster stew is often made with only heavy cream, oysters, and butter, but a healthier alternative can be created with evaporated milk and added vegetables, such as potatoes, pearl onions, carrots, or mushrooms.
Scallops
Like clams and oysters, scallops are bivalves (two-shelled mollusks). Scallops propel themselves along the ocean floor by clapping their shells together using a well-developed muscle called the eye, the part of the scallop that is eaten.
If you avoid fish and other types of shellfish, you may still like scallops because its eye is firmer than most shellfish meat and its flavor is mild yet sweet. Scallops are rich in vitamin B12 and potassium.
Scallops are classified in two broad groups: bay scallops and sea scallops. Bay scallops, with meat about 1/2 inch in diameter, are sweeter, more succulent, and more expensive. Sea scallops, with meat about 1 1/2 inches in diameter, are more widely available. A third type is the calico scallop, a small sea scallop from Florida, but it is often sold as bay scallops. These scallops have to be steamed to be opened, so they are partially cooked when sold. They are the cheapest of the scallops.
Because scallops cannot close their shells tightly, they spoil quickly out of water, and they are usually shucked at sea. The muscle is iced and the rest discarded. Sometimes the coral-colored roe is left attached to be eaten with the muscle as a delicacy.
Look for scallops with a sweet smell and a fresh, moist sheen. Avoid any with a strong sulfur odor. Scallops can range in color from pale beige to creamy to orange. Avoid those that are stark white, a sign that they have been soaked in water as a marketing ploy to increase the weight. Refrigerate shucked scallops immediately after purchase and use within 1 to 2 days.
Preparation Tips
Scallops must be opened like oysters if purchased unshucked. Some sea scallops still have a small piece of tough connective tissue attached to one side, which should be pulled off and discarded. Scallops need only brief cooking. Overcooking or reheating cooked scallops will toughen them. The roe, if attached, can be cooked right along with the muscle. Large scallops should be sliced into smaller pieces.
Serving Suggestions
Scallops are suitable for a variety of preparation methods, including sauteeing, grilling, broiling, and poaching. They also are used in soups, stews, and salads. Scallops cook very quickly — about 1 to 3 minutes — and no scallop needs to cook longer than 6 to 8 minutes, no matter how large.
Shrimp
Shrimp is the most widely consumed seafood worldwide, and it is the second most popular in the United States, after tuna. The harvest of both wild and farmed shrimp is increasing rapidly to keep pace with the soaring demand for this crustacean. It has become popular internationally because its sweet, mild, and yet distinct flavor is similar to that of lobster, but it is easier to cook and costs half as much.
Although hundreds of species are caught, shrimp generally can be classified by origin — either warm water or cold water. Cold-water varieties — such as the well-known small, pink, peeled shrimp — tend to be sweeter than the larger shrimp, which typically develop in warmer waters. These larger varieties are often sold uncooked and unpeeled under the name "prawns," but the name can be used for shrimp of any size.
The names of shrimp can be confusing. Many varieties of shrimp are named after a color (white, pink, brown), but white shrimp are not necessarily white. They may look pink, brown, or gray. Confounding the problem, most shrimp shells change color when cooked.
Shrimp are marketed according to size (number per pound), but market terms vary greatly. Because shrimp freeze well, most, even those classified as "fresh" in the supermarket, have been frozen at some point. Neither taste nor texture suffers much.
Shrimp is sold shelled or unshelled, raw or cooked, and fresh or frozen. Shrimp also can be bought breaded or stuffed or as a spread for crackers or bread. Dried shrimp and shrimp paste can be found in Asian grocery stores.
Preparation Tips
Choose raw, shelled shrimp that are firm, moist, and translucent. Avoid any shrimp that smells like ammonia. Unshelled shrimp should have shiny, firm shells. Avoid those with black spots and those with yellow or gritty shells, which result from a bleaching process to remove the spots.
Before storing fresh, uncooked shrimp, rinse them well under cold, running water and drain thoroughly. Refrigerate, tightly covered, for up to 2 days.
Shrimp are usually shelled before they are eaten, which is easily accomplished by peeling back the head first, then the rest of the shell. Shelling is easier when shrimp are cold or even frozen. Shrimp are also usually deveined, although this is not necessary before eating small to medium-sized shrimp. To devein a shrimp, cut into the shrimp lengthwise with a sharp knife. Then use the knife to remove the dark vein — which is actually the intestine that runs down its back.
Although there are slight differences in texture and flavor, shrimp of various sizes (except the miniatures) can usually be substituted for each other.
As with all shellfish, shrimp should be cooked briefly or it becomes tough and rubbery. Cook only until the flesh turns opaque. To test, cut a shrimp in half, and check whether the flesh has turned from translucent to opaque. Whole shrimp should just begin to curl. If the shells are on, they should turn pink.
Serving Suggestions
One reason for the popularity of shrimp is its versatility. Name a cooking technique, and you probably will be able to find a shrimp recipe for it. Shrimp is served cold in shrimp cocktail. It can be grilled, boiled, broiled, roasted, curried, or stir-fried. It goes well with pasta and rice. It is also an excellent ingredient in soups and can be used interchangeably with other shellfish in recipes. Garlic is a seasoning that particularly complements shrimp’s flavor. The two are used together in well-known dishes such as shrimp scampi.
