Whether it's steak & lobster or linguine & clams, shellfish is a popular choice at market seafood counters or restaurants. Shellfish can be divided into two main categories; Crustaceans and Mollusks, and due to the vast size of this topic this will be the first of three installments. This being said, I will discuss the main aspects of these two divisions without focusing on one particular type of shellfish in too much detail. This column and the next installment will concentrate on the aspects of crustaceans and the third column will focus on mollusks.
All shellfish are invertebrate sea creatures, meaning that they do not have an internal bone system like fish which are called vertebrates. Almost all shellfish have a hard outer shell that protects their soft bodies from predators and the environments they thrive in. Crustaceans is the grouping that represent crabs, lobsters, shrimp, crayfish, etc. I will focus on crabs and lobsters in this column, while leaving the discussion on shrimp, prawns and crayfish for the next.
Buying shellfish live is almost always preferred, but many don't have this option at their marketplace. When live is an option, it is usually only crabs and lobsters in the crustacean family that are available.
There are many ways to cook a live crab or lobster. The most common way is to submerse it headfirst into a pot of boiling water to kill it instantly. Crabs are then boiled for approximately six to 10 minutes depending on their size, and lobsters are usually five to six minutes per pound. Due to the labour required of picking the dispersed meat from crabs, they are almost always cooked this way rather than trying to extract raw flesh which is more difficult. Another option for killing lobsters is to hold it down firmly on a cutting board and plunge the tip of a chef's knife into the head before cooking it. This should be done immediately before cooking it to ensure optimal freshness and flavour, as the rule of thumb for raw crab or lobster is to cook it in the live form. Raw crab and lobster flesh deteriorates very rapidly.
Lobsters are also very tasty if split in half and opened up, brushed with oil, lemon juice, and seasonings and then grilled on the barbeque. When splitting in half, you can cut right through to serve as two halves, or cut from the underside but not all the way through the top shell and serve as a whole split lobster. If prepared in this manner, you will want to weigh down the tail portion as it will curl up and lose contact with the grill. Another way to avoid this is to cut the tail section completely through while leaving the body halves connected by the top shell. This way you are able to curl the tail to the sides of the lobster and should not need to be weighted down. With either grilling option, the large claws should be cracked beforehand as this will assist in cooking the claw meat at the same speed as the exposed body and tail flesh.
When working with or eating whole crab or lobster, the stomach in both cases is located just behind the eyes, and should be removed and discarded. With crabs, the feathery gills located on each side of the body under the shell are also discarded.
Dear Chef Dez:
I know it's better to buy live shellfish, but our grocery store only offers frozen crab legs. Are they cooked already? For a nice crab dinner, how do I cook them and for how long?
Harold M., Saskatchewan
Usually frozen crab legs are already cooked prior to freezing, and the easiest way of preparing them is in a steamer. Submersing them in boiling water, which is a preferred technique for live crabs, will cause more flavour loss with frozen crab legs rather than steaming. The amount of cooking time will depend on the size of the crab legs. Bring a couple of inches of water to a full boil in a pot while in the meantime arranging your crab legs as evenly as possible in a steamer basket. Once the water is boiling, place the filled steamer over the water and immediately cover with a lid. Normally the cooking process should take anywhere from 6 to 10 minutes, but the safest way is to use an instant read thermometer. There is almost always a cracked part of the shell to allow for the thermometer to be inserted. Find the thickest flesh to do this with, and serve when the internal temperature reaches 170 degrees Fahrenheit. They are best served simply with dishes of warming melted butter for dipping.
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Chef Dez is a Food Columnist, Culinary Instructor & Cooking Show Performer. Visit him at www.chefdez.com