Shrimp are decapod crustaceans with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata. More narrow definitions may be restricted to Caridea, to smaller species of either group or to only the marine species. … Shrimp are widespread and abundant.

Shrimp and prawn are types of seafood that are consumed worldwide. Although shrimp and prawns belong to different suborders of Decapoda, they are very similar in appearance and the terms are often used interchangeably in commercial farming and wild fisheries. A distinction is drawn in recent aquaculture literature, which increasingly uses the term “prawn” only for the freshwater forms of palaemonids and “shrimp” for the marine penaeids.^[rx]

Caridea which is also known as Caridean shrimp belongs to the phylum Arthropoda and order Decapoda. It lives in both salt and fresh water. Mostly the carideans are omnivorous. The body of the shrimp is divided into three categories such as head, thorax, and abdomen (tail). Shrimp have short legs and two pairs of claws. It is small in size. Some of the shrimp are hermaphrodites and have separate sexes. They are able to change the sex from male to female. About 2800 species of shrimp are found in the world.  The shell of shrimp is hard that is colorless or transparent due to which it becomes difficult to see in the water. As they are small, it becomes a prey to predators such as fish, crabs, starfish, sea urchins, whales, puffins, sharks, dolphins, and humans.

Types of Caridean Shrimp

1. White Shrimp

These shrimp are large in size with a tender texture and mild flavor. It adds texture when it is combined with sauces or seasonings. It has a mild flavor. It is mostly used in soups, pasta, and curry.

2. Brown Shrimp

It is not large like white shrimp but possesses a more vigorous flavor. It has a firm texture and is used in thick stews or kinds of stuff. It has a strong flavor. It is mostly used in stuffing and etouffee.

3. Black Tiger Shrimp

The shrimp having black and white striping in the back is Black Tiger shrimp. It is inherent to Southeast Asia. It has a mild flavor and firm texture. It is mostly used with strong seasonings and chili.

4. Mexican Shrimp

It has white, blue and brown varieties. It has got superior taste and firm texture. It is usually served in cocktail style, main entrée, and pasta.

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Brown, White, and Pink Shrimp

When most Americans think of shrimp, they’re envisioning brown, white, or pink shrimp.

• Brown shrimp mostly come from the Gulf of Mexico, though they’re found down the entire Atlantic coast. They like it warm, so they’re found in shallow waters, and tend to be fairly small with a purple-ish coloring on the tail. Firm in texture, their flavor isn’t the strongest, though they’re thought to have a distinctive mineral-y iodine shrimp flavor.
• White shrimp tend to be a little more tender and sweet. With a slightly lighter color and a green-hued tail, they’re found along the Atlantic and Gulf coasts in shallow, muddy waters. There’s also a good number of white shrimp imported from Latin America—especially Mexico and Ecuador—Thailand, and China, all with varying levels of sustainability ratings (see the seafood watch reports for more details.)
• Pink shrimp are some of the tastiest shrimp you can find, mild and sweet without the distinctive ammonia taste some of the brown and white shrimp have. Just don’t expect a vibrantly hued patch of shrimp at the market—pink shrimp can range from white to gray in color. You can recognize them by dark blue coloring on the tail; they usually also sport a spot on either side of the body, about three-quarters of the way to the tail.
• Tiger Shrimp – Found mostly in Asia, especially in Thailand, Vietnam, Taiwan, and China, tiger shrimp have telltale brown striping on their bodies. There are currently non-native tiger shrimp populations found off the Eastern Coast of the United States as well. They can get enormous in size, up to a foot long, and are the most commonly farmed shrimp in the world. Farmed or fresh, they can have a distinctly shrimpy flavor, though you might want to check seafood watch for reports on its environmental impact in Asian farms. You’ll frequently find them frozen in five-pound blocks in Asian markets.
• Spot Prawn – Generally, among English-speakers, the word “prawn” is used more in the UK, Europe, and Australia, while the word “shrimp” is more common in North America. Some people may have the mistaken impression that a prawn is necessarily a bigger creature than a shrimp (possibly due to the other meaning of the word shrimp). In reality, there’s no rhyme or reason to nomenclature beyond regional preference. Yet for whatever reason, even in the US, the spot prawn is always referred to as a prawn and not a shrimp. It’s found along the Pacific coast from Alaska down to Mexico and is a delicacy in British Columbia and the Pacific Northwest. A fairly large shrimp, at up to a foot long, spot prawns are prized for their sweetness and tenderness.
• Rock Shrimp – Rock shrimp are deepwater residents, growing tough and hardy in the cold waters off the Atlantic coast from Virginia down to the Gulf. A few species also live off the Pacific coast. They don’t look at all like their warm water cousins, boasting a very hard (dare I say rock-like) shell and segmented flesh that looks more like a lobster tail than anything else. It tastes, not surprisingly, kind of like lobster, more firm than other varieties of shrimp, but also sweeter. It’s excellent in preparations that typically call for lobster, and a whole lot cheaper to boot. It’s pretty much impossible to remove that tough shell without a dedicated machine, so it’s usually sold pre-peeled.

Health Benefits of Shrimp

Caridean measures about a few millimeters in length when it is grown fully. It has one pair of stalked eyes. It is packed with Vitamin D, protein, Zinc, and Vitamin B3. It is food free from carbohydrates. It possesses cancer-preventive, anti-inflammatory, and anti-aging properties that help to lower health problems. It provides relief from eye fatigue, menstrual pain, and macular degeneration.

1. Lose weight

It is an excellent source of Vitamin D and protein. Zinc in high amounts helps to increase the level of leptin in the body which plays a vital role to regulate appetite and fat storage appetite. The high presence of leptin avoids the problems such as inexplicable cravings and overeating. (1)

2. Slows down aging

Skin aging is a common problem that is caused due to sunlight. The sunlight exposure or UVA results in spots, wrinkles, and sunburn. The addition of shrimp to the diet promotes skin health. It has a high content of astaxanthin which is an antioxidant that helps to lower the chances of skin aging associated with sunlight and UVA. The addition of a shrimp cocktail to the diet lowers the chances of skin wrinkles and spots. (2) (3)

3. Macular degeneration

The studies show that heparin is a compound that helps to cure neovascular AMD. Shrimp has astaxanthin which provides relief from eye fatigue. (4) (5)

4. Prevent hair loss

The minerals in Shrimp help to promote hair health. Hair loss is caused due to a deficiency of zinc. It has a vital role in the formation of new cells such as skin or hair cells. (6)

5. Cardiovascular problems

The shrimp paste possesses a fibrinolytic enzyme which is essential for thrombolytic therapy which breaks the harmful blood clots in the blood vessels. It helps to prevent the chances of cardiovascular ailments. The high content of Omega-3 fatty acid eradicates the cholesterol in the bloodstream. It also lowers the chances of strokes and heart attacks. (7)

6. Brain function

The high content of iron in Shrimp is essential for the process of bonding oxygen in hemoglobin. Iron assists in to rise inflow of oxygen to muscles provides endurance and strength. It also increases the flow of oxygen to the brain. The study shows that astaxanthin assists to promote memory performance, lowers brain diseases, and the survival of brain cells. (8) (9) (10)

7. Anti-cancer properties

Shrimp has astaxanthin that helps to lower the chances of cancer. It also possesses selenium that reduces the chances of cancer such as lung and prostate cancer. Selenium counteracts free radicals that could lead to cancer. It upgrades the immune system and inhibits the tumors that grow in blood vessels. (11) (12) (13)

8. Lowers menstrual pain

Shrimp has omega-3 fatty acids which is beneficial cholesterol that balances the adverse effects of Omega-6 fatty acids and also helps to eradicate menstrual cramps in women. It promotes the flow of blood in reproductive organs by lowering the damage of cholesterol. (14)

https://www.youtube.com/watch?v=a-t3C1VzTm8

Precautions 

1. Mercury

Shrimp has a high content of mercury which is harmful to human health. It could lead to vision problems, mercury poisoning, and lower fetal health. It should be consumed in moderate amounts to avoid mercury poisoning.

2. Purines

The high amount of purines in the body could be harmful to the person who is suffering from gout. It has high amounts of purine which could be harmful to gout patients that are caused due to high presence of uric acid.

3. Food Allergies

Shrimp might cause allergic reactions. The high intake of seafood could increase the chances of allergic reactions.

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How to Eat         

• Shrimp could be boiled, grilled, broiled, baked, and fried.
• The chopped shrimp is combined with chopped tomatoes, scallions, garlic, diced chili peppers, lemon juice, and olive oil. It could be served on a salad.
• The cold and cooked shrimp is served with salsa dip.
• Cut up cooked shrimp and add it to vegetable soups.
• The cooked shrimp could be added to the spicy pasta sauce which could be added to the wheat noodles.
• It is used as an ingredient in salads, appetizers, and chowders.
• Scampi is a shrimp that is broiled or sautéed in butter and garlic.

Other Facts

• The legs, rostrum, and eyes grow out of the hard shell.
• It lays about one million eggs that hatch in two weeks.
• It could live in both saltwater and freshwater.
• Americans consume about one billion shrimp in a year.
• May 9 is regarded as National Shrimp Day.
• Some could live up to six and half years.
• Shrimp is born a male which turns to female when they get mature.
• It has ten legs.
• Uncooked shrimp is called green.

Handling shrimp at sea

Care of the catch begins before the cod end comes on board a shrimp trawler. The trawl has to be towed long enough to get a reasonable catch, but unnecessarily long hauls can damage the shrimp in the net. Some fishermen claim that a weighted cod end makes subsequent sorting easier; when the cod end comes up vertically shrimps and flatfish tend to remain in the bottom of the cod end, while round fish move up towards the lengthening piece. It is also said to be possible to give the shrimp a preliminary wash by towing the trawl near the surface just before hauling. The efficacy of these techniques has not been examined first hand.

Once the shrimp are on board, they must be handled quickly and carefully. Exposure to sun and wind on deck should be avoided, otherwise, spoilage will be increased and chilling made more difficult. An awning should be rigged over the deck in warm weather.

The catch is first sorted or culled; other fish, dead or damaged shrimp, and rubbish are removed by hand or by sieve. The shrimp are then washed thoroughly in seawater to remove any remaining mud or sand and to reduce bacterial contamination. The shrimp are drained as much as possible and are then ready for further processing, usually freezing, cooking, or chilling.

FREEZING ON BOARD

Shrimp are not frozen at sea on any British trawler at the present time, although the practice is now commonplace in some overseas fisheries, for example in the Gulf of Mexico. The economics of freezing the deep-water shrimp catch at sea, on the Fladen ground, for example, maybe worth examining in terms of improved quality and increased proportion of fishing time to steaming time.

Shrimp can be frozen at sea by immersion in a cold brine or a solution of sugar and salt, by air-blast freezing, or by plate freezing. Immersion and air blast freezers are used successfully on shrimp vessels in North and Central America. Freezing in sugar and salt solution is claimed to give an improved glaze on the shrimp, and to make separation of the shrimps easier when thawing.

Deepwater shrimps can be frozen in 10-15 minutes by immersing them in brine at -20°C. Very long immersion times result in an unacceptable product because of excessive uptake of salt. Shrimp can also be frozen satisfactorily in blocks 50 mm thick in a vertical plate freezer; the shrimp are poured into a polyethylene bag between the freezer plates, and the spaces between the shrimp are filled with water. The freezing time for a 50 mm block in a plate freezer operating at -35°C is 90 minutes. The added water gives protection against physical damage to the shrimp, provides better contact during freezing, and reduces dehydration of the shrimp during subsequent storage. The frozen blocks may need further wrapping, for example in fibreboard cartons, to make them easier and safer to handle on a moving ship.

Cooked whole shrimp can be frozen satisfactorily in a plate freezer in the same manner as raw shrimp, but immersion freezing of cooked shrimp is unsatisfactory because the thawed shrimp are difficult to peel, and the texture of the meat is poorer.

COLD STORAGE OF WHOLE SHRIMP

Frozen shrimp should be stored at sea at -30°C. The frozen shrimp can be transferred to shore cold storage at -30°C on arrival at the port, or thawed immediately for further processing.

COOKING ON BOARD

Cooking immediately after capture helps to retain the best flavor and color, but food poisoning bacteria can grow rapidly on the product if it becomes contaminated after cooking. In order to reduce the risk of food poisoning, the cooked shrimp must either be frozen on board immediately or landed and processed ashore the same day. Chilled storage of cooked shrimp at sea for several days cannot be recommended.

Cooking time must be as short as possible; slow-boiling results in poor flavor and texture, and the shrimp lose more weight. After sorting and washing, the shrimp are tipped into briskly boiling seawater; batches must be small enough to allow the shrimp to move freely in the water. Densely packed shrimp will not cook uniformly. The ratio should be about 1 kg shrimp to 5 liters water, and the heat input should be sufficient to cook the shrimp in 6-7 minutes. A typical shipboard boiler may hold about 90 liters of water, and when 18 kg shrimp at 10°C are tipped into this amount of seawater boiling at 101°C, the water temperature will fall to about 86°C.

The water in a shrimp boiler should be changed as often as possible; dissolved protein and dirt in the water may accelerate the production of off odors and flavors in the shrimp.

After removal from the boiler, the shrimp are cooled. On small inshore shrimp vessels, this is often done by immersing the shrimp in seawater or by spreading them out on clean canvas or wire mesh trays in the open air. Cooling in seawater can contaminate the cooked product, and canvas or trays are extremely difficult to keep clean. Cooling by evaporation also results in some weight loss. Where possible the cooked shrimp should be packed in polyethylene bags and surrounded by ice; the shrimp can be kept chilled in this way until they are landed later the same day or are frozen on board.

CHILLING ON BOARD

After sorting and washing, the raw whole shrimp are drained and packed in ice in shallow boxes; the time between catching and chilling must be short. A delay of an hour or so on a warm day can cause considerable spoilage.

The box should be no more than about 200 mm deep to avoid crushing the bottom shrimp. A layer of flake ice or finely crushed block ice should be placed at the bottom of the box. A layer of shrimp, not more than 50 mm deep should be laid on the ice and covered with more ice. Successive layers of shrimp and ice are then added until the box is full. Boxes must not be overfilled, or shrimp will be crushed when boxes are stacked. The shrimp should still be well covered with ice when they are landed; if they are not, then insufficient ice has been used. As much as 1 kg ice to 1 kg shrimp may be needed in an uninsulated fish room in summer. The fish room temperature should be kept at 1-3°C so that the ice melts slowly; meltwater should be free to drain from the bottom of a box.

Raw whole deepwater shrimp stowed in crushed ice will keep in good condition for up to 4 days, but for best results, the iced shrimp should be processed onshore within 2 days of capture. The typical shrimp flavor disappears completely after 6 days in ice and the meats become soft, discolored, and difficult to peel; after 8 days sour fishy odors and flavors develop. Shrimp processing plants onshore should not use iced raw material more than 4 days old for subsequent cooking, peeling, and freezing.

Discoloration due to melanosis, or black spot as it is commonly called, is not a serious problem in shrimp from UK grounds, because it normally does not occur until after the shrimp have spoiled so much as to be already unacceptable.

Refrigerated seawater, raw, can be used as an alternative to ice for the storage of raw whole shrimp at sea. The shrimp will keep in good condition for up to 4 days in row at 0°C, but for best results, they should be processed onshore within 2 days of capture. A suitable stowage rate is 2 kg shrimp to 1 liter of water; the seawater can be refrigerated mechanically or by the addition of ice.

Deepwater shrimp stored in row have a generally more attractive appearance than iced shrimp of the same age; the raw whole shrimp look cleaner and have better pink color, and the cooked meats are again pinker than their iced counterparts. There is some uptake of salt; raw raw shrimp contain about 2 percent by weight of salt after 2-3 days storage, which is normally an acceptable concentration.

Handling shrimp onshore

Whole raw shrimp should be processed at factories close to the ports of landing. Unless freezing facilities are available onboard the catcher, all processing, including cooking, is better done ashore. Inshore species of shrimp, as well as deepwater shrimp, can be cooked and further processed onshore under more hygienic conditions with little loss of quality if they are iced at sea immediately after capture.

FREEZING OF WHOLE SHRIMP

The methods described earlier for freezing shrimp at sea are equally applicable onshore, provided the chilled raw material is frozen within 2-3 days of capture; the thawed product can then be used for further processing in the same way as fresh shrimp.

COLD STORAGE OF WHOLE SHRIMP

Whole shrimp, raw or cooked, frozen individually in air blast or in blocks with water in a plate freezer, will keep in good condition in a cold store at -30°C for at least 6 months. Individually frozen whole shrimp will keep for 3-4 months in good condition at -20°C, and for only 1 month at -10°C; whole shrimp stored at -10°C are more difficult to peel when thawed. Blocks of shrimp with added water will keep a little longer at these temperatures, up to 6 months at -20°C and 2-3 months at -10°C. It is recommended that wherever possible whole shrimp being stored for an indefinite period should be kept at -30°C.

Raw and cooked frozen whole shrimp develop cold store odors and flavors during storage, and the higher the storage temperature, the more quickly they develop. Shrimp cooked after freezing and cold storage are usually paler in color than shrimp that are cooked before freezing. Both raw and cooked whole shrimp must be adequately protected against dehydration during cold storage, either by glazing or by suitable packaging; the shell of the shrimp provides no protection. Glazing should be inspected periodically and renewed as required.

THAWING OF FROZEN WHOLE SHRIMP

Blocks of whole shrimp frozen at sea or onshore can be thawed in air or water. Thawing times for a typical commercial block measuring 1050 mm × 530 mm × 50 mm thick and containing about 18 kg shrimp and 6 kg water are as follows; 20 hours in still air at 18°C, 2 hours in saturated moving air at 18°C, 1½ hours immersed in water at 18°C and 1 hour in a water spray at 18°C. The water spray method is the fastest because the fine jets help to break up the block as individual shrimp thaw on the surface, thus exposing a greater surface area. With each of the methods, the blocks are soft enough to break up by hand before the shrimp are fully thawed, but it is difficult to do this without damaging some of the shrimp.

The thawed shrimp can be further processed in the same way as whole chilled shrimp.

Individually frozen shrimp can be thawed in a few minutes, or they can be cooked directly from the frozen state.

SIZE GRADING

Whole raw shrimp on receipt at the factory are first graded for size, since large shrimp are generally more valuable than small ones, and mechanical peelers require a supply of shrimp within a fixed size range. Small shrimp that are uneconomic to peel are either discarded or are used in the chopped form as raw material for various products.

COOKING

Shrimp are cooked to provide a product that is ready to eat and to loosen the meat in the shell prior to peeling.

The cooking process can be more easily controlled onshore than at sea; more space is available, better heating systems can be used, and instrumentation is more practicable. A short brisk cook is better than a long slow one. The ratio of shrimp to water should be as low as possible so that the water returns to a boil as quickly as possible after the shrimp have been put in. With a ratio of 1 kg shrimp to 20 litres of water, the temperature of the water will fall initially to about 95°C, and there should be sufficient heat available to bring it back to the boil in 1-2 minutes. The water in the boiler should contain 3-5 percent salt; the use of stronger brines can cause discoloration of the meats during subsequent chilled storage.

Cooking time is important; about 3 minutes is usually sufficient for UK shrimp, but the precise time for a certain size or quality of shrimp should be determined by experiment. The boiling time should be long enough to develop fully the flavour and texture of the shrimp meat, and to loosen the meat from the shell; overcooking can destroy the flavor and can cause loss of weight.

A lidded wire mesh basket can be used for immersing the batches of shrimp, and the basket of shrimp should be agitated gently in the water to ensure uniform cooking. Scum should be removed from the surface of the water as often as possible, and the water in the boiler changed frequently, preferably several times a day.

COOLING

The shrimp should be cooled immediately after cooking. Cooling in the air is claimed to give the whole cooked shrimp a better color but, unless the shrimp are to be marketed in this form, it is recommended they be cooled in water. The yield of meat from water-cooled shrimp can be up to 4 percent higher than from air-cooled shrimp. They can either be immersed directly into chilled water for about 3 minutes until they are at a temperature of about 0°C, or they can be cooled in two stages, first in water at tap delivery temperature and then in chilled water. The latter method will be more economic in terms of ice or mechanical refrigeration. The shrimp should never be left to soak any longer than is necessary to chill them. As soon as they are down to chill temperature, they should be lifted out, drained, packed in clean boxes, and transferred either directly to the peeling area or into a chill room. Water and ice used for cooling must be clean; hygiene is important, and a chlorination system may be necessary.

PEELING

Brown shrimp and pink shrimp from inshore waters are still normally peeled by hand, but machines are now available that will handle the larger deepwater shrimp.

In hand peeling, the body of the shrimp is held in one hand, and the head twisted off with the other. The first two or three segments of the shell are then broken open with the thumb, and the tail is squeezed to release the meat. A skilled worker can peel 2½-3 kg whole shrimp an hour.

American and Danish peeling machines are now available commercially that can handle deepwater shrimp. Successive pairs of rollers behead the shrimp, split the shell along the back, and pull the shell from the meats. Output depends on the size of shrimp, but a single machine can peel as much shrimp as 16 hand workers.

Shrimp are often consumed without any further cooking; therefore particular attention must be paid to hygiene and sanitation. Regular bacteriological control of processing is important for this type of product. The main source of bacterial contamination of cooked shrimp is the peeling process, particularly hand peeling. Workers must wash their hands frequently, and all working surfaces must be kept scrupulously clean. Recommended procedures for factory cleaning are given in Advisory Note 45 ‘Cleaning in the fish industry. The use of chlorinated water on the processing line can be of considerable help in keeping down contamination, but shrimp waste must not be allowed to accumulate since the chlorine is rapidly inactivated by protein. The shrimp must be kept cool throughout the process.

Machine peeling results in far less recontamination of cooked shrimp than hand peeling. Provided the peeling machines are cleaned at frequent intervals, the risk of increasing spoilage or introducing food poisoning bacteria is much less with machine peeling than with hand peeling.

Where raw meats are required for further processing, thawed frozen whole shrimp are much easier to peel than very fresh unfrozen shrimp. Peeling of unfrozen shrimp becomes easier after 1-2 days of chilled storage.

YIELD AND PACKING DENSITY

The yield of meat from whole shrimp is variously quoted as ranging from 20 to 45 percent, but it is not always specified whether the yield is from raw or cooked whole shrimp. The head constitutes about 40 percent of the weight of whole raw shrimp, and the tail shell and legs a further 15 percent; the yield of raw meat is thus about 45 percent. The yield of cooked, peeled meats from samples of raw whole deepwater shrimp, weighed first after freezing and thawing and again after cooking and hand peeling, is about 28 percent. The weight loss during a 3-minute cook is about 26 percent, and a further 46 percent is lost during hand peeling. If the initial weight is taken to be that of the whole cooked shrimp, the yield on hand peeling is about 38 percent. There is little difference between yields from large deepwater shrimp, counting 190/kg, and medium-sized ones counting 320/kg.

Packing densities, based on a few measurements of samples of deepwater shrimp, are provisional as follows

DIPPING

A number of dipping treatments between peeling and freezing of deep-water shrimp have been tried in British trade practice, in order to improve flavor or color. For example, salt, monosodium glutamate, citric acid or sodium citrate, polyphosphate, and dye have all been, or are being, used at some stage in the process. The value of some of these treatments is questionable. Where dipping solutions are used, they should be kept chilled and renewed at frequent intervals to prevent bacterial contamination of the cooked meats.

The meats are sometimes dipped in a 3-7 percent salt solution when the salt uptake during boiling is found to be insufficient. Monosodium glutamate is used to enhance flavor, and the use of polyphosphate is claimed to reduce weight loss on thawing. Citric acid or sodium citrate is used to reduce the discoloration of meats, and dye is used to give a uniform pink color; the dye is sometimes added at the cooking stage. Most if not all of these treatments should be unnecessary on good quality shrimp meats handled and processed expeditiously.

FREEZING OF MEATS

The peeled meats can be frozen individually or in blocks. Individually quick frozen, IQF, meats are particularly suitable for catering and retail outlets since the required amount can be dispensed from the pack without thawing. Meats in blocks suffer less weight loss during freezing, and are better protected in cold storage, but have the disadvantage that a complete block has to be thawed and used at one time.

IQF meats can be frozen in either an air blast freezer or a liquid nitrogen freezer. The air blast freezer can be either a batch or continuous type, but delays between the freezer and cold store are more likely with a batch freezer, and individual small meats can warm quickly during this time; continuous freezers are therefore recommended to ensure a steady flow of frozen meats from freezer to the cold store. The fluidized bed type of freezer is used for freezing individual shrimp but, where the meats are moved through the freezer entirely by agitation in air, there is some weight loss in the form of pulped meat or mush, which may have to be recovered and utilized in some way. A modified form of fluidized bed freezer is available that overcomes this difficulty by agitating the meats just enough at the start of freezing to ensure that they are individually frozen and then moving them by belt through the remainder of the freezing process.

IQF meats of deepwater shrimp require a freezing time of about 10 minutes at -30°C in air moving at 5 m/second. Liquid nitrogen freezers are compact and can freeze shrimp meats quickly; a freezing time of 3½-5 minutes is typical, but they are expensive to operate, and a high degree of utilization is essential in order to keep down the cost. Sheets of plastic film or trays with nonstick surfaces may have to be used to prevent the meats from adhering to the freezer belt. If the meats are not laid out individually, some inevitably stick together, and separation of these before packing adds to the labor cost.

Blocks of shrimp meats are normally prepared by packing the meats into trays or molds and freezing them in a horizontal plate freezer. The trays are slightly overfilled so that there is compacting during freezing to give a homogeneous block. A typical block is 25-30 mm thick. The freezing time for a 25 mm block in a horizontal plate freezer operating at -35°C is about 40 minutes. The frozen blocks are usually packed in cartons with an inner wrapper, and then moved to a cold store. Alternatively, the shrimp may be cartoned before freezing; the freezing time for a 25 mm block in a carton is about 50 minutes.

PACKING AND GLAZING

Individually quick frozen meats for sale to caterers and retailers are normally weighed into flexible film bags which are sealed and packed in fibreboard outer cartons for storage and distribution. The film used for the individual packs should have a high resistance to the passage of water vapor and oxygen so that dehydration and oxidation are kept to a minimum; for example, a laminate of polyethylene and polyester, or a single polyamide film, is suitable.

The individual meats are often glazed, that is dipped in cold water to coat them with ice, before packing them, to protect the product against drying in cold storage. However, packing in sealed film bags is sufficient to protect the unglazed product under good commercial conditions. Vacuum packing will give added protection against the possibility of occasional poor commercial cold storage. It is extremely difficult to control the amount of ice picked up by small meats during glazing, due to variation in size and temperature of the frozen product, the temperature of the glazing water, and the duration of the dipping or spraying process. The proportion of glaze to total glazed weight can vary from 10 to 40 percent. The weight of glaze is usually included in the declared weight of contents of consumer packs, and the resulting loss of weight on thawing can cause customer dissatisfaction. Successful prosecutions have been brought against processors for excessive application of glaze to shellfish meats.

The addition of glaze also results in considerable warming of the product, and it may be necessary to refreeze in order to avoid imposing an excessive heat load on the cold store. Meats frozen in liquid nitrogen are often at a low enough temperature to cause the glaze to shatter and become ineffective as a protective barrier. For all these reasons it is strongly recommended that the practice of glazing individual meats for sale to caterers and retailers be discontinued and replaced by adequate packing.

Blocks of shrimp meats can be glazed as an alternative to protective packaging, or they can be wrapped in a suitable plastics film and packed in fibreboard outers. Bulk lots of individually frozen meats awaiting further processing can also be glazed before storage. It must be remembered that glazed products in cold stores must be inspected periodically and the glaze renewed as required.

COLD STORAGE OF MEATS

Frozen cooked shrimp meats should be stored at -30°C; they will keep in good condition at this temperature, provided they are properly wrapped or glazed, for at least 6 months. Long-term storage at higher temperatures is not recommended; for example, after 3-4 months at -20°C, the development of undesirable odor and flavor and poor texture can make the product unacceptable.

CANNED SHRIMP

Shrimp meats are not canned commercially in the UK at the present time. Typical North American practice may serve as a guide to those considering the possibilities of canning. The peeled meats are blanched by immersing them for 2-3 minutes in boiling water containing 6-8 percent salt, cooled and drained on a conveyor, and packed by hand into cans lined with a sulfur resistant lacquer. For a typical wet pack, hot brine containing 2-3 percent salt is added to the can, and sometimes a small amount of citric acid is added to reduce iron sulfide discoloration. The cans are closed without exhausting at about 65°C and then heat processed in a retort. A 150 g can require about 10 minutes at 120°C or 20 minutes at 115°C. A 250 g can require about 12 minutes at 120°C or 35 minutes at 115°C. The cans are cooled to about 38°C in the retort, then removed, dried, and stacked for about 48 hours before labeling, cartooning, and storage. Sometimes a dry pack is made by blanching the meats for 8-10 minutes and packing them in parchment-lined cans without brine. The cans are evacuated, sealed and heat processed for about 60 minutes at 120°C, or 85 minutes at 115°C, for a 150 g can.

The wet pack process can be modified for packing shrimp meats in the glass.

SMOKED SHRIMP

Cold smoked products can be made from shrimp. Whole headless shrimp, or peeled meats, are boiled in a 10 per cent salt solution for about 3 minutes, drained for about 2 hours, laid on oiled mesh trays, and smoked in a mechanical kiln for 1-1½ hours at 30°C. The yield of headless smoked shrimp from whole raw shrimp is about 36 per cent. The brining and smoking treatments can be varied to suit particular tastes.

POTTED SHRIMP

In the UK cooked peeled meats are heated in melted butter, sometimes with added spices, and then ladled into containers, typically waxed cartons; the mixture is left until the butter has set, lids are put on and the cartons are wrapped in greaseproof paper and packed in outer cartons for dispatch. The product is highly perishable and should be sold within 1-2 days of manufacture.

OTHER SHRIMP PRODUCTS

Shrimp meats can be used in the preparation of a number of seafood products, including pastes, spreads, crisps, soups, bisques, sauces, and other prepared dishes, most of which can be stored for long periods after freezing or canning. It is not possible within the space of this note to give individual methods of preparation.

Composition of shrimp

Raw shrimp meat contains 75-80 percent water, 18-20 percent protein, and about 1 percent fat; cooked meat contains 65-70 percent water, 25-30 percent protein, and about 1 percent fat. The calorific value of cooked shrimp meat is about 4.5 kJ/g. Vitamins A and D are present in small quantities.

Shrimp waste

Shrimp waste, that is heads and shells, can be used to produce a shrimp meal containing 40-45 percent crude protein and 5 percent moisture after cooking, drying and grinding. Chitin and its derivative chitosan have also been extracted from shrimp waste on a commercial scale in North America. Glucosamine hydrochloride, which can be derived from shell waste, has been suggested as a possible commercial source of glucosamine.

Small whole shrimp are also sometimes cooked and dried on the Continent and used for feeding poultry and farmed trout; the shrimp are boiled for 4 minutes and then placed on mesh trays in a suitable drying kiln for about 8 hours.

Precautions 

• The consumption of sea fish if one is trying to reduce inflammatory diseases such as heart disease.
• Farmed ones contain arsenic that leads to arsenic poisoning.
• Seafood should be cooked safely in order to prevent foodborne illness.
• Pregnant women, young children, older adults, people having lower stomach acid and compromised immune systems (HIV/AIDS, liver disease, cancer, diabetes, gastrointestinal disorders, people taking steroids, chemotherapy, or immune system) are prone to higher risk.
• It might be contaminated with bacteria such as Vibrio parahaemolyticus, Vibrio vulnificus, and other bacteria relate to land use, sewage discharges, runoff, etc. These microorganisms occur naturally in warm coastal waters which could cause even death or serious illness in individuals who are at higher risk.
• Listeria monocytogenes could cause a serious foodborne illness known as listeriosis.
• The virus Hepatitis A could survive in light cooking. So one should consume it after being properly cooked.
• Fish could have toxins that could cause illness such as ciguatoxin and scombrotoxin, or histamine poisoning.
• Sea fish is related to Scombrotoxin (histamine) which develops when fish is not kept cold enough. The symptoms develop quickly and also disappear completely within 24 hours.
• The flesh of tropical marine fishes might cause ciguatera poisoning experiencing gastrointestinal maladies that could last for several days, weakness in arms and legs, and reversal inability to differentiate between cold and hot. The symptoms could persist for weeks.
• Farmed seafood results in to increase in inflammation leading to weight gain, arthritis, and heart diseases.
• The imbalance ratio of Omega-6 and Omega-3 causes heart disease and hypertension.
• Seafood and fish in farms have polychlorinated biphenyls (PCBs), organophosphorus (OPs), organochlorine (OC), trifluralin pesticides, and hexachlorobenzene (HCB) causing diseases or even death.
• The seafood has a high content of mercury, which may lead to mercury toxicity.
• Consume it in moderate amounts. So consume it with caution or Avoid consuming it raw.
• Some people might get allergic reactions. So avoid it.
• It has a high chance of contamination.
• One should limit its intake.
• Consult the doctor by pregnant women and children before consuming it. Children and pregnant women should avoid it because the high content of mercury might cause a negative impact on the development of the nervous system of a fetus.
• Seafood or fish have purines in it which is harmful to people having purine-related problems. Excess purines result in an excess buildup of uric acid that could lead to the formation of kidney stones as well as gout.

References

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