Shellfish Basics

Reading Guide

Before You Read

Think of an Example Look over the Key Concepts for this section. Think of an example of how or when you could use one of the skills from the Key Concepts. Thinking of how you might apply a skill can help motivate your learning by showing you why the skill is important.

Content Vocabulary

• PUFI mark

• crustacean

• mollusk

• sleeper

• univalve

• devein

• bivalve

• cala mari

• cephalopod

• escargot

• barnacle

• surimi

j IQF (individually

quick frozen)

Shellfish is a tasty treat that can be used in many dishes.

Read to Learn

Key Concepts

• Explain the structure, composition, and grading of shellfish.

• Differentiate between types of mollusks.

• Distinguish between types of crustaceans.

• Identify other types of seafood.

Main Idea

Shellfish meat is expensive and often considered a luxury. Shellfish is versatile, however, and can be used in appetizers and soups as well as main courses.

Graphic Organizer

As you read, use a category tree like the one shown to organize the categories of shellfish. In the first set of boxes, fill in the three types of shellfish. In the next set of boxes, fill in examples of each type.

Academic Vocabulary

• luxury • mandatory tj Mathematics

NCTM Number and Operations Understand numbers, ways of representing numbers, relationships among numbers, and number systems.

NCTM Problem Solving

Apply and adapt a variety of appropriate strategies to solve problems.

NCTE National Council of Teachers of English NCTM National Council of Teachers of Mathematics

NSES National Science Education

Standards NCSS National Council for the Social Studies


l Graphic Organizer Go to this book's Online Learning Center at ™ for a printable graphic organizer.

Shellfish Basics

Shellfish are often considered a luxury, or expensive and extravagant, food. Shellfish meat is expensive because much of the body of the animal is not used for special dishes. However, shellfish appear in many places on the menu. They can be found as appetizers, in soups, and as entrées. Every foodservice professional should know how to select and prepare shellfish.

Structure of Shellfish

Unlike fish, shellfish have no bones. They have hard shells that cover their bodies. Shellfish are found in both fresh water and salt water. Two types of shellfish are mollusks ('ma-lssks) and crustaceans (,kr9s-'ta-shens).

People eat many different parts of shellfish. Muscles, legs, tails, claws, and tentacles are all used in various dishes. Sometimes shellfish are eaten whole, with or without the shell. Most shellfish are lean and composed primarily of water, vitamins, minerals, protein, and fats.

Learning to prepare shellfish takes time and practice. Each type has special physical characteristics that must be taken into account. For example, some need to be removed from the shell before cooking, while others are cooked in the shell.

Inspection and Grading

Fish and shellfish are inspected, just as meat and poultry are. Although grading is not required, the U.S. Department of Commerce (USDC) will inspect and grade fresh fish and shellfish for a fee. The inspection of frozen and canned fish is mandatory, or required.

Fish are inspected for accurate labeling, safety and cleanliness in preparation, and wholesomeness. Grading is done to be sure that the fish meet standards for flavor and appearance. Because there are so many kinds of fish, the USDC has set criteria for only the most common types of fish.


The USDC inspects fish and shellfish in one of the following three ways:

• Type 1 inspection covers processing methods and the processing plant itself. The product receives a PUFI mark if it is safe, clean, accurately labeled, and has a good flavor and odor. A PUFI mark means Packed Under Federal Inspection. (See Figure 21.4.)

• Type 2 inspection covers things such as labeling, weight, and packaging.

• Type 3 inspection is for sanitary conditions only.


Fish are graded based on standards for flavor and appearance. Only fish inspected under Type 1 criteria can be graded. Fish may be judged as Grade A, B, or C. Processed or canned products are either B or C quality.

• Grade A Highest quality, no physical defects, good odor and flavor

• Grade B Good quality

• Grade C Fairly good quality

I Describe What is Type 3 inspection of shellfish?

L iFSBTf Fish Inspection

PUFI Mark The Packed Under Federal Inspection mark given by the USDC covers processing methods and the processing plant. What does this mark mean when seen on a package of shellfish?

Packed Under Federal Inspection


A mollusk is a shellfish that has no internal skeletal structure. Instead, it has a shell that covers its soft body. Mollusks are classified in three major groups. The groups are divided according to the kind of shell the mollusk has.

A univalve (lyu-ni-1valv), such as conch, has a single shell. A bivalve (=bl-ivalv) has two shells that are hinged together. Common examples of bivalves include mussels, oysters, and clams. Instead of an outer shell, a cephalopod (ise-fs-ls-ipad), such as squid or octopus, has a thin internal shell. Cephalo-pods have tentacles, or false legs, attached to the head near the mouth.


Oysters can be purchased any time during the year, but they are best to eat in the fall, winter, and spring. Oyster meat is very delicate and has a high percentage of water. Because the salts, nutrients, and minerals of the water flavor the meat, oysters within the same species may taste different, depending on where each was harvested. Also, the flavor can be watery and bland during warmer months when oysters reproduce.

Market Forms

Oysters may be purchased live, shucked, or canned. A shucked oyster has had the meat removed from the shell. Shucked oysters can be purchased either fresh or frozen and range in size from very small to extra large. They are graded by size, as shown in Figure 21.5. Canned oysters are rarely used in commercial kitchens.

Handling and Storage

When you purchase live oysters, check that the shells are tightly closed or that they close quickly when they are tapped. If they do not move, they are dead and should be thrown away. Oysters should have a clear appearance and be plump. Both shucked and live oysters should have a sweet, mild odor.

Store live oysters in cardboard containers in the cooler. They should be draped with seaweed or damp towels. Check oysters daily, and throw out any dead ones. If the oysters have already been shucked, keep them in containers surrounded by ice on all sides, and keep the harvesting tag. Fresh oysters should keep for up to a week in the refrigerator.

Before you open oysters, scrub their shells. Then, place them on a sheet pan in a hot oven until the shells open. The oysters can then be removed from the shell. If a shell does not open, throw away the oyster. Oysters can also be removed raw from the shell but this can be dangerous and takes skill and practice.


Clams are harvested from both the West Coast and the East Coast. Types of clams from the West Coast include the razor clam, rock clam, and butter clam. Clams from the East Coast are known by their shells. They either have a soft shell or a hard shell. Soft-shell clams may be called steamers or longnecks. Hard-shell clams are also called quahogs (iko-ihdgs) and are classified according to size. Chowder clams are the largest clams. Cherrystone clams are the second largest. The smallest clams are called littlenecks.

1FIGURE21.5 Oyster Grades

Purchase Oysters Oysters are graded by size, and are best eaten during the fall, winter, and spring. Why do you think summer harvested oysters are not as popular?

Grade of Oysters

: Number per i Gallon

Very Small

more than 500

Small or Standards


Medium or Selects


Large or Extra Selects


Extra Large or Counts

160 or fewer

Market Forms

Like oysters, clams should be purchased live for the greatest freshness. They should smell fresh and sweet. Clams may be purchased in three forms:

• Shucked, either frozen or fresh

• Canned, either chopped or whole

Handling and Storage

Treat clams carefully so that their shells do not break. Store live clams in cardboard containers or in their original containers in the refrigerator for up to one week. Do not store in a sealed environment. Like oysters, they must be kept damp.

Scrub hard-shell clams before you open or cook them. Soft-shell clams can be sandy inside. Some chefs like to soak soft-shell clams in water for a few hours with salt or cornmeal. The clams eat the salt or cornmeal and expel the sand. However, clams can die due to lack of oxygen so they must be kept in large amounts of water or the water must be changed every 30 minutes.

Gourmet Math

Bulk Discounts

Shellfish is typically sold in bulk. Many vendors offer quantity discounts.

Mai Ling's seafood supplier sells medium oysters at $75 per gallon. The supplier offers several quantity discounts: a discount of 5% off the total price for buying at least 10 gallons of oysters, 10% for at least 15 gallons, and 20% for at least 20 gallons. Mai Ling's restaurant needs 9 gallons of oysters per day. What is the average daily cost if she buys a one-day supply each day? If she buys a two-day supply every two days? If she buys a three-day supply every three days?

jMH^SflE Calculate Discount Price

Calculate the discount price by multiplying the original price by (100% minus the discount percentage).

Starting Hint When she buys a two-day supply, or 2 X 9 = 18 gallons, Mai Ling will receive a 10% discount. The new price will be 100% - 10% = 90% of the regular price. Multiply 0.90 X 18 X $75 to find her two-day price, and divide by 2 for the average per day.

NCTM Number and Operations Understand numbers, ways of representing numbers, relationships among numbers, and number systems.

Mollusk Varieties There are many different varieties of mollusks available. How are clams classified?

Many Mussels

Blue mussels and greenshell mussels can be used in a variety of dishes. Why should fresh mussels be


Mussels come from around the world. Mussels look like small, dark blue or black clams. Their meat generally ranges from yellow to orange in color and is tender but firm when cooked.

Mussels from Southeast Asia and New Zealand have a green edge to their tan or light gray shells, and white or orange meat. Flavor is not affected by the color. These mussels are generally more expensive.

Market Forms

Mussels may be sold live, shucked, vacuum packed, or frozen in the shell. The shells of live mussels should be closed or should close when tapped lightly. Throw out any mussels that seem hollow or are very lightweight. If the mussels are too heavy, they are most likely filled with sand, and should also be thrown away. If mussels have been shucked, they are generally packed in brine to preserve them, or sold frozen. Live or fresh shucked mussels must be used quickly because they can become toxic after they die.

alive just before they are cooked?

Handling and Storage

When you prepare mussels, scrub the shells under cold running water. Use a clam knife to scrape off any barnacles ('bar-ni-ksis) that have attached themselves to the shells. A barnacle is a crustacean that attaches itself to rocks, boats, or other sea life. Just before cooking, pull off the mussel's "beard," which sticks out between the two shells. If the mussel is sandy, soak it in water and cornmeal to get rid of the sand.

Keep mussels in the refrigerator and away from light. Store them in the paper sack or cardboard box they arrive in, and keep the container damp.


Scallops are available year-round and are sweet in flavor and white in color. They generally are sold already shucked. The muscle that closes the shell is the only part of the scallop that is commonly eaten in the United States. If scallops smell fishy or strong, they have spoiled or aged.

Sea scallops and bay scallops are the two most common kinds of scallops. Sea scallops are the largest, with about 10 to 40 per pound. Bay scallops are small and more delicately flavored, and range from about 50 to more than 150 per pound.

Market Forms

Scallops are sold fresh and shucked by the pound or the gallon. They may also be sold frozen, in five-pound blocks, or IQF. IQF (individually quick frozen) fish or shellfish have been quickly frozen piece by piece. The freezing happens quickly, so few ice crystals form. This improves the quality.

Handling and Storage

Remove the little side muscle that is attached to the large adductor muscle on the sides of scallops. The adductor muscle opens and closes the valves on a bivalve mollusk. Although scallops can be prepared with the side muscle attached, this muscle tends to be very tough. Cover and refrigerate scallops. Do not place them directly on ice or they will become watery and lose their flavor. Sometimes large sea scallops are cut into smaller pieces before they are cooked.

the proper way to store mussels?


A crustacean has a hard outer shell and a jointed skeleton. Examples include lobster, shrimp, crab, and crayfish. Crustaceans tend to be expensive because so much work is needed to produce a small amount of meat. Restaurants often purchase crustaceans already processed to save preparation time. This will also save restaurant money in labor costs for chefs to prepare the meat. Crustaceans can be prepared in almost any way, as long as they are not overcooked. Overcooking makes them tough.


Northern lobsters may be considered the most valued seafood delicacy. This animal has two large claws, four pairs of legs, and a flexible, large tail. The lobster shell, which turns red when cooked, is actually bluish or dark green. Lobster meat from the tail, legs, and claws is sweet and white. Lobsters can weigh up to about 20 pounds. Rock, or spiny, lobsters are warm-water lobsters. They are sold only as IQF lobster tails.

Cooked lobster meat smells sweet and fresh. If a lobster is in the process of dying, it is called a sleeper. Sleepers should be cooked at once so that the meat will still be good. Once lobster meat has been cooked, cover and refrigerate it. The meat will keep only for a day or two.

Market Forms

Lobsters are sold live, frozen, or as fresh-cooked meat. Uncooked lobster tails are also available IQF.

Handling and Storage

The lobster must be split and cut for some preparations, such as broiling or cubing for use in stews or sautés. When you cook live lobster, plunge it head first into boiling water.

Live lobsters should be stored in special saltwater tanks. They can also be kept in a cool location, wrapped in seaweed or heavy, wet paper.


Shrimp are classified by the count per pound. The smaller the shrimp, the higher the count. It takes less work to peel and devein large shrimp, but they are more expensive. To devein ((,)de-'van) a shrimp means to remove its intestinal tract, located along the back. Deveined shrimp cost more and are sold either raw or cooked. It takes about a pound of raw shrimp to make a half-pound of peeled and cooked shrimp.

Continue reading here: Peel and Devein Shrimp

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  • Murray
    What happens to most kind of shellfish when they are overcooked?
    3 years ago
  • outi
    Who inspects molluscan shellfish and tags for food service?
    5 years ago