9420.pdf

Raw shrimp are held on ice for about 2 days after catching to allow proteolytic enzymes
and microorganisms the time to break down connective tissue between meat and shell
to improve peelabilty. This deterioration also increases water-holding capacity and the
holding period results in an increased bacterial load on the raw shrimp (Nielsen et al.,
1983).
Iced shrimp are dumped into a melt/feed tank where potable water is continuously
introduced to melt the ice and distribute the shrimp on the precooker conveyor. In the
precooker, live steam is injected to provide optimum peeling and recovery of meat. In the
precooker, the microbial load is reduced. The precooked shrimp fall onto the oscillating
rollers of the peeler which pull extraneous parts from the meat. Water sprays loosen and
wash away waste. Waste and the sprayed water are flumed away to a waste sump.
From the peeler the shrimp fall into the first of several flumes which lead to cleaning and
separating steps. Mesh belt conveyors and elevators permit the flume water to pass
through the mesh belt and onto the floor, from where it is discharged. After mechanical
cleaning operations, the shrimp are flumed onto a table or “picking belt” where workers
hand sort and clean the shrimp. Shrimp meat is salted by spraying with a salt solution
or immersing it in a salt tank. Shrimps are often hand-packed into cans, vacuum sealed,
and refrigerated or frozen. A typical flow diagram of shrimp processing is illustrated in
Figure 4.4 (Horn and Pohland, 1973).
4.5.2 Crab Processing
Crabs are harvested from shallow water and transported to a processing plant. The
crabs are loaded into baskets, briefly rinsed with tap water and then loaded into cookers.
After the crabs are loaded and the cooker closed, steam is applied. The baskets are then
removed from the cooker and stored overnight in a walk-in refrigerator. The backs and
claws are then removed and the remaining viscera washed free. The crab meat is then
either manually or mechanically picked and placed in plastic containers for shipment to
market. A typical crab processing flow diagram is presented in Figure 4.5 (Horn and
Pohland j 1973). Claws may be canned whole or the meat extracted and canned. The
edible meat produced from the crab is only 10 to 15 % of the total live weight before
cooking.
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