King Crab

Three species of king crab harvested in the North Pacific and Bering Sea are of commercial importance. The most important species is red king crab (Paralithodes camtscha-

tica). Blue king crab (P. platypus) is caught in commercial quantities primarily near the Pribilof Islands. Brown or golden king crab (Lithodes aequispina) are found in deeper waters at the edge of the continental shelf.

King crabs are actually not "true crabs" like dungeness, tanner, or blue crab, but are more closely related to an order of hermit crabs. The legs of true crabs are jointed forward, whereas the legs of king crabs are jointed to fold behind its body (5).

Harvesting

The world's most extensive king crab populations dwell in Alaskan waters, where 15-year-old male king crabs may grow to a weight of 24 lb and a leg span of 6 ft. Most of the commercial catch consists of 7- or 8-year-old crabs that weigh about 6 lb. They are captured by means of large pots consisting of iron frames about 6 ft square and 3 ft high covered with synthetic webbing. These pots may weigh between 300 and 700 lb apiece. The pots are baited with fresh fish (herring is the most preferred) and then dropped to the bottom at 60 to 300 ft depth with a heavy line and marker buoy. The pots are lifted every few days and the male crabs of legal size are kept. The crabs are held alive on the vessel in a well with circulating seawater. At the docks or on the deck of a processor vessel, the live crabs are transferred to seawater tanks to await processing. Weak crabs may be sorted out and processed immediately, but generally all dead and injured crabs are discarded.

Processing

The crab is butchered by use of a stationary iron blade. The back, or carapace, is removed and the crab is split into halves, each with legs attached, called sections. A quick shake will jar out viscera that cling to the body cavities. Revolving nylon brushes are generally used to clean off gills and viscera.

Batch cooking is common, although a continuous cooker requires less labor, and cooking is done without the delay of filling a basket. It also has automatic steam controls and a fixed rate of travel through the tank, ensuring identical cooking. For crab planned for frozen sales, the sections are cooked for 22 to 28 min in either boiling fresh water or seawater. Cook times will vary slightly, but cooking should be continued to ensure that the internal temperature of the crab meat reaches at least 88°C (190 °F).

For canned or retorted products, crab need only be cooked to make meat removal easy. A two-stage cook of 20 min at 60°C (140 °F), rinsing the sections well with a spray of water followed by cooking in boiling water for 12 min, has been proposed (6). This prevents a blue discoloration in canned Kegani crab since the crabmeat is coagulated during the precook while the blood (hemocyanin) can be washed free of the meat. Regardless of cooking method, cooked crab meat should be picked and thermally processed as rapidly as possible to ensure an excellent canned product (7). Normally, canned crabmeat is packed in 307 by 113 C-enamel cans, sealed in a vacuum, retorted for 50 min at 116°C (240°F), then water cooled (8).

For freezing, the sections are cooled in cold running water after cooking. Ideally, chilled water is used to cool the sections to at least 4°C (40°F). Usually, sections are then frozen either in brine or air-blast freezers. The majority of Alaskan king crab production is brine-frozen. The sections are packed with the legs stacked in the center of baskets, shoulders out, and held in liquid brine (22-23%) at a temperature of -18 to — 20°C (0 to — 5°F) for 30 to 60 min. Internal temperature should reach at least 15°F. The sections are then removed from the brine and dipped in cold fresh water to rinse the salt from the section and to form a protective glaze on the surface of the crab. Blast freezing freezes the product in air by blowing refrigerated air (less than - 30°C or - 20°F) over it. Proponents of blast freezing contend the method results in a product with a lower sodium content. Brine freezing, if carefully controlled, will be similar to blast freezing, and some feel it results in a moister product.

Product Forms

Almost all of Alaska's king crab is sold frozen. Frozen king crab is packed in a variety of product forms, including both in-shell products and extracted crab meat. The most common king crab products include the following.

Bulk Clusters (Sections). These are packs of shoulders, legs, and claws, commonly packed in 80-lb random weight cartons. The pack should average about 75% legs and 25% shoulder-body meat by weight.

Legs and Claws. These packages are available in a number of forms, including both whole legs and claws or split legs and claws. King crab have six walking legs, two of which have claws. Packs of legs and claws should be in equivalent proportion to the live crab and should include the whole leg from shoulder to walking tip or claw. As a general rule, the larger the leg the higher the price.

King Crab Meat. The body, leg, and claw meats are removed by shaking or by blowing with water under pressure. After the shoulder-body meats are removed, each leg is broken just below the uppermost joint and the two connective tendons that run through the leg meat are removed by pulling the remaining leg sections free. This step is repeated for each leg segment, allowing the leg meats to be removed intact. For larger industrial processes, the legs are divided at the joints, in some cases, by use of a band saw, and fed into two large rubber rollers. The rollers are adjusted for proper clearance and are continuously rotated so that the shell is squeezed as it passes through and the meat is forced out. Meat yield averages about 20% but may be 26% or more by weight of the live crabs (9,10).

The meats are washed, sorted, inspected for shell and debris, and packed into cartons or trays for freezing. King crab meat is available in a number of forms including:

Merus meat. The red-colored merus meat is the largest segment of a king crab's leg and the most expensive. It is available in both blocks and individually quick frozen (IFQ) in poly bags.

Fancy meat. The most common pack of king crab meat and consists of a mixture of merus meat (25-35%), shoulder-body meat (40-50%), and red leg meat (30-35 %). The blocks of meat are packed in triple layers beginning with the merus meat, then white meat, finally red leg meat, and then frozen. The higher the percentage of leg meat in the block, the higher the price. Salad meat. Salad meat is a cheaper frozen pack of small chunks of both red and white meat. Rice meat. The cheapest form of king crab meat is rice meat, which consists of uniformly shredded body and leg meats.

King crab that is adequately protected from dehydration can be held for six months or more at —18 to — 23°C (0 to - 10°F).

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