Phytogeny of commercially important seafood and description of the seafood industry

Clinical Reviews in Allergy r 1993 by Humana Press tnc. 0731-8235/93/159-181/$5.60

Phylogeny of Commercially important Seafood

and Description of the Seafood industry

M. W. Moody,*,1 K. J. Roberts, 2 and ,1. V. H u n e r 2

~Louisiana Cooperative Extension Service, Louisiana Agricultural Center and Louisiana Sea Grant Program;

and 2University of Southwestern Louisiana

Phylogeny Life arose in the seas and all major phyla are represen ted in

the waters of the world~ Most are edible and are consumed in at least small amounts somewhere. Presented here, however, are only those major groups t ha t are current ly impor tan t in Nor th America, or tha t have widespread value on the in te rna t iona l level and may become subsequen t ly impor t an t in Nor th America . These include both ver tebrates (reptiles, amphibians , and fishes) and inver tebra tes (echinoderms, crustaceans, and mollusks).

There are nont rad i t iona l species in North American waters and elsewhere. These will become more impor tan t in years to come as populat ion pressures force highly developed societies to make bet ter use of animal protein resources. In some societies, mar ine mammals are an impor tan t source of protein. "Exotic" to Western culture, creatures such as the jellyfishes (coelenterates) are widely consumed seafoods in other areas of the world. Fer- mented fish sauces in Southeas t Asia utilize a potpourri of smal l c rus taceans and fishes t h a t would otherwise be discarded in Nor th America. Such fish sauces represent vital sources of pro-

*Author to whom all correspondence and reprint requests should be addressed.

Clinical Reviews in Allergy 159 Volume 11, 1993

160 Moody, Roberts, and Huner

rein and a possible option to the seafood processing waste problem in the West. The primitive jawless fishes called lampreys and hagfishes (Class Agnatha) are destroyed because they are predators of more traditional fishes. They may also be considered edible. Aquatic plants, although seaweeds are important foods in the Orient, are not discussed.

The various aquatic animals important as foods for Western culture are presented below based on ecological associations and phylogenetically within those associations. This follows from the various commercial fisheries, including aquaculture, that target them. It must be realized by the reader, however, that the aquatic environment is a continuum. Therefore, freshwater species are found in low salinity areas of estuaries, estuarine species move in and out of freshwater and marine environments, and marine species move in and out of estuarine environments. Anadromous species like salmon, striped bass, and shad spawn in freshwater but mature in marine and estuarine areas. Catadromous species like angui]lid eels and many true mullets mature in freshwater but spawn in marine and estuarine environments respectively. All too frequently common English names describe species that have no close phylo- genetic relationships. Common names used here are based on those utilized by the North American seafood industry (1,2). Taxonomic classifications do change more often than one would like. However, we have used nomenclature provided by Lagler et al. (3) and Walls (4) for fishes and Barnes (5) for invertebrates.

Seafoods are among the most diverse and numerous of all flesh foods consumed by humans. Historically, humans have relied on seafoods as a significant source of protein and recreation. Today, seafood harvesting, processing, and distribution is performed on an international scale.

Vertebrates Reptiles (Phylum Reptilia)

Marine Turtles

Freshwater Alligators Turtles-Soft-Shell and Snappers

Amphibians (Phylum Amphibia) Frogs

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Phylogeny of Seafood 161

Fishes (Phylum Pisces) Primitive Fishes (Class Chondrichthyes-cartilagenous fishes)

Sharks (Order Squaliformes) Rays (Order Rajiformes)

Advanced Fishes (Class Osteichthyes-bony fishes) Freshwater

Sturgeons and Paddlefishes (Order Acipenseriformes) Bowfin (Order Amiiformes) Gars (Order Lepisosteiformes) Trouts, Chars and Whitefishes (Order Clupeiformes-

Suborder Salmonoidei-Family Salmonidae) Smelts (Clupeiformes-Salmonoidei-Osmeridae) Pikes (Clupeiformes-Esocoidei-Esocidae) Carps (Order Cypriniformes-Cyprinoidei-Cyprinidae) Buffalos (Cypriniformes-Cyprinoidei-Catastomidae) Catfshes (Cypriniformes-Siluroidei) Eels (Order Anguilliformes) Pike-Perches and Perches (Order Perciformes-Percidae) Cichlids, especially Tilapias (Perciformes-Cichlidae)

Estuarine Salmon (Clupeiformes-Salmonoidei-Salmonidae) Herrings, Shads, Sardines, and Anchovies (Clupeiformes-

clupeoidei) Milkfish (Clupeiformes-Chanoidei-Chanidae) Drums, Weakfishes, and Croakers (Perciformes-Sciaenidae) Striped Basses (Perciformes-Suborder Percoidei-

Percichthyidae) Mullets (Perciformes-Suborder Mugiloidei-Mugilidae) Flatfishes (Order Pleuronectiformes)

Marine Reef Fishes

Groupers and Sea Basses (Perciformes-Percoidei- Serranidae)

Snappers (Perciformes-Percoidei-Lutj anidae) Porgies (Perciformes-Percoidei-Sparidae) Grunts (Perciformes-Percoidei-Pomadayidae) Parrotfishes (Perciformes-Percoidei-Scaridae) Puffers (Order Tetraodontiformes-Tetradontidae)

Demersal Fishes Cods, Pollocks, Whitings, and Hakes (Order Gadiformes

Gadidae) Orange Roughy (Perciformes-Trachichthyidae)



Rocldishes and Ocean Perches (Perciformes-Percoidei Scorpaenidae)

Tile Fishes (Perciformes-Percoidei-Branchiosteigidae) Sablefishes (Perciformes-Suborder Cottoidei-

Anoplopomagdae) Lumpfishes (Perciformes-Suborder Cottoidei-

Cyclopoteridae) Wolffishes (Perciformes-Blennioidei-Anarb/chadidae) Monkfishes and Anglerfishes (Order Lophiiformes-

Lophiidae) Pelagic Fishes

Bluefishes (Perciformes-Percoidei-Pomatomidae) Jacks and Pompanos (Perciformes-Percoidei-

Carangidae) Dolphins (Perciformes-Percoidei-CorTphaenidae) Mackerels and Tunas (Perciformes-Suborder

Scombroidei-Scombridae) Billfishes (Perciformes-Suborder Luvaroidei-

Istiophoridae) Swordfishes (Perciformes-Suborder Luvaroidei-

Xiphiidae) Butterfishes (Perciformes-Suborder Stromatoidei-

Stromateidae) Barracudas (Perciformes-Suborder Sphyraenoidei-

Sphyraenidae) invertebrates

Echinoderms (Phylum Echinodermata) Sea Urchins (Class Echinoidea) Sea Slugs (Class Holothuroidea)

Crustaceans (Phylum Arthropoda-Class Crustacea-Order Decapoda)

Clawed Lobsters (Suborder Reptantia-Superfamily Nephropsidea)

Spiny Lobsters (Reptantia-Superfamily Scyllaridea) Freshwater Crayfishes [crawfishes] (Reptantia-Nepl-Lropsidea) Cold Water Marine Shrimps and Freshwater Prawns

(Suborder Natantia-Section Caridea) Warm Water Marine Shrimps (Natantia-Section Penaeidea) Crabs (Reptantia)

Cancer Crabs (Family Canceridae) Swimming Crabs (Family Portunidae) Stone Crabs (Family Xanthidae)



Cold Water Long-legged Crabs [Dungeness, King, Snow, Tanner] (Family Grapsidae)

Mollusks (Phylum Mollusca) Bivalves (Class Pelecypoda)

Clams and Cockles (Order Heterodonta) Oysters, Mussels, and Scallops (Order Anisomyaria) Deep Burrowing Clams (Order Adapeodonta)

Snails (Class Gastropoda) Abalones (Order Archaeogastropoda) Conches (Order Mesogastropoda) Whelks (Order Neogastropoda)

Cephalopods (Class Cephatopoda) Octopusses (Order Octopoda) Squids (Order Decopoda)

Production The seafood industry is, in general, poorly documented from

a statistical standpoint. This is the case nationally and interna- tionally. Much of the emphasis has been on generating data for the management of fisheries. This focus on the harvest aspect is merited because continuous production from fish stocks aids the industry and consumers. However, at the harvest level the data are so highly aggregated and delayed that application to decision making is limited. The situation has improved since the passage of the Fisheries Conservation and Management Act of 1976 by the United States Congress. This act authorized management of domestic fishery resources out to 200 miles offshore. Fisheries management plans (FMP) for many species were developed as a result. Each FMP and subsequent amendment documents serve as references containing the best scientific and statistical data available. Plans include information on the regulatory and processing aspects of the particular fishery resource being managed.

Regulatory professionals, investors, and others utilize annual publications reflective of the United States industry that a r e issued by the National Marine Fisheries Service (NMFS). This agency is part of the National Oceanic and Atmospheric Administration in the United States Department of Commerce. Four publications serve to depict many aspects of domestic and world fishery product use:

i. Fisheries of the United States (6)--published annually and available in May or June of each year,



2. Frozen Fishery Products (7)--published annually, 3. Processed Fishery Products (8)--published annually and gener-

ally available after a year's lag, and 4. Imports and Exports of Fishery Products (9)--published annu-

ally and generally available in April or May of each year.

The considerable t rade in fresh and processed f ishery products necessitates an international perspective when dealing with fisheries. Many fish species routinely cross national boundaries and are occasionally managed by international agreements. A comprehensive source of production and trade reflecting the international use offish species is the Food and Agricultural Orga- nization (FAO) of the United Nations. Two volumes are produced for each calendar year. The FAG Yearbook of Fishery Statistics-- Catches and Landings (10) is generally available two years following the reported year. Approximately 980 species items are listed on alive weight basis. The yearbook is inclusive of freshwater and marine animal species along with aquatic plant production by country.

Seafood Supplies The foundation of inquires into mar ine species production

for indust r ia l and food uses is reliable data~ The abovement ioned references provide baseline da ta tha t can be supplemented by species, product, location, and time-specific information when available. In the aggregate, world fisheries production more t h a n tripled between 1954 and 1989 (6). Supply of edible and nonedible species increased from 28 million metric tons (MT), live weight basis, to 100 million MT. The si tuat ion is in contrast to a fre- quent ly s ta ted conclusion tha t the oceans have reached maxi- m u m production. The farming off ish by artificial means was jus- tiffed, in part , by a forecast leveling off of world f ishery supplies. In absolute t e rms there was no stal l ing of the increase in n a t u r a l f ishery supplies. Supplies increased in 17 of 20 years be tween 1970 and 1989. There remains an element of accuracy to supply forecasts. In relat ive terms, the supply growth ra te from n a t u r a l fisheries was not increasing. In relation to an increasing interest among consumers, marketers anticipated demand growth pro- ceeding faster than supply. The supply situation depicted in Table i supported more consumption but not without increased supplies from farms and generally rising prices.


Phylogeny of Seafood

Table 1 World Commercial Catch of Freshwater

and Marine Species, 1970-1989

Million metric tons (round weight)

Freshwater Marine Total

1970 8.4 59.7 68.1 1971 9.0 59.5 68.5 1972 5.7 58.5 64.2 1973 5.7 57.0 62.7 1974 5.8 60.7 66.5 1975 6.2 60.2 66.4 1976 5.9 63.9 69.8 1977 6.1 62.8 68.9 1978 5.8 64.8 70.6 1979 5.9 65.2 71.1 1980 6.2 65.8 72.0 1981 6.6 68.2 74.8 1982 8.5 68.7 77.2 1983 9.3 68.3 77.6 1984 10.0 73.9 83.9 1985 10.7 75.7 86.4 1986 11.8 81.0 92.8 1987 12.7 81.6 94.3 1988 13.4 85.4 98.8 1989 13.8 85.7 99.5

165

F r o m 1970 to 1989 wor ld f i sher ies p roduc t ion i n c r e a s e d 46% to 99.5 mi l l ion MT. This is 83% of the 120 mi l l ion MT po ten t i a l i den t i f i ed by Bell (11). Var ied g rowth r a t e s a re ev iden t a f t e r cal- cu la t ion from Table 1. Growth t o w a r d the b e n c h m a r k po ten t i a l w a s slow d u r i n g the 1970s. World p roduc t ion i nc r ea sed by only 3 mi l l ion MT (4.4%). The following decade p roduced a 27.5 mi l l ion MT (38%) inc rea se in total wor ld ha rves t . W h e n v i e w i n g wor ld h a r v e s t by f r e s h w a t e r a n d m a r i n e componen t s , t r e n d s w e r e dif- f e ren t . The smal l wor ld f i sher ies p roduc t ion i nc rea se f rom 1970 to 1979 was inc lus ive of a 2.5 mi l l ion MT (30%) dec rea se in t h e f r e s h w a t e r component . M a r i n e p roduc t ion i n c r e a s e d 5.5 million MT (10.2%) for t he s a m e per iod of t ime.

The 1980-1989 per iod g rowth in abso lu te t e r m s was l a r g e s t in t h e m a r i n e f i sher ies . Supp ly i n c r e a s e d by 19.9 mi l l i on MT

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(30%). Freshwater supplies for the period showed a larger relative increase of 123% (7.6 million MT).

The distribution of supply increases during the major growth period, 1980-1989, was uneven. World leading suppliers, the former U.S.S.R. and Japan, were in a near no supply growth mode. China, Chile, and Peru each more than doubled their fisheries production. The United States supply increased by 2.1 rail- lion MT (58%). The United States and Japan in the role of major producers also are noteworthy from the import perspective. Japan as the leading importer on the basis of value mainta ins a wide margin over the United States in second place. The complexity of world trade is exemplified by the United States' role as the world's leading exporter of fishery products. United States exports are dominated by West Coast salmon and surimi. Imports are dominated by white fish fillets and steaks, tuna, and shrimp. These imports are pnmari ly in raw frozen form. Canned tuna is the country's largest category of value added products.

J apan and the United States as large economic forces in the market attract the higher valued species from the world's producing nations. Production by species groupings indicates the relative role offish and shellfish in world supplies (Table 2). From 1985 to 1989 world production of all species increased 15%. Shell- fish at a 22% increase exceeded the growth in finfish production (14%). Finiish increases were largest among the herring category and the "other" category. The world's production of the species yield- ing white flesh was essentially unchanged. Cods, lakes, baddocks, and flatfish are particularly important as United States imports.

The disposition of the world's production over the 1985 to t989 period exhibited little change. The process of reducing fish to meal and oil claimed 27.7% of supply in 1989 (Table 3). Frozen products were the next highest usage at 23.4%. The use of supplies as fresh marketed products increased in four of the five years. This may be a reflection of improved supply services as transportation improvements occur and/ or of consumers paying more for the perceived value of fresh product.

Seafood Supply: United States Seafood harvesters in the United States demonstrated an

abili ty to increase landings over the 1987-1989 period. Landings increased 73% (Table 4). The exvessel value increased 433% to

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Table 2 World Commercial Catch Finfish and Shellfish, 1985-1989

167

Million metric tons round weight

Finfish Shellfish Total

1985 76.0 10.4 86.4 1986 81.8 11.0 92.8 1987 82.0 12.3 94.3 1988 86.2 12.6 98.8 1989 86.8 12.7 99.5

Source: Fisheries of the United States,

Table 3 Disposition of World Catch, 1985-1989

% of total

1985 1986 1987 1988 1989

Marketed fresh 18.6 19.5 21.0 22.2 21.3 Frozen 23.9 23.6 23.6 23.1 23.4 Canned 13.3 12.5 12.4 12.0 12.1 Cured 14.8 14.1 14.5 14.0 14.1 Meal and oil 27.9 29.0 27.2 27.4 27.7 Miscellaneous 1.5 1.3 1.3 1.3 1.4

approx $3.8 bill ion. However , w h e n the va lue was placed on a ba s i s t h a t r emoved in f la t ion , the i nc r ea se w a s a c t u a l l y 58%. L a n d i n g s for h u m a n food accounted for all of t he increase . Land- ings for indust r ia l purposes, such as meal and oil, failed to increase d u r i n g th i s period.

She l l f i sh l and ings increased s l igh t ly for the period (Table 5). The va lue of l and ings increased approx 45%. E s s e n t i a l l y all of t he she l l f i sh va lue increase could be r e l a t ed to the effects o f inf la - t ion. The f inf ish l and ings inc reased d r a m a t i c a l l y for t he per iod w i t h t he h a r v e s t of pollock in A l a s k a the ma jo r deve lopmen t of the decade. The edible supply s i tuat ion for the decade also inc luded 2 mi l l ion MT (round weight ) of impor t s in 1980. Impor t s r eached the record level of 3 mi l l ion MT in 1987 before dec reas ing to 2.6 mi l l ion MT. She l l f i sh comprised 22% of 1990 impor t s for a 49% s h a r e of value , i n 1980 she l l f i sh s imi l a r l y accounted for 49% of impor t va lue bu t amoun ted to only 17% of impor ts . A majo r fac-

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Table 4 Unites States Commercial Catch and Value 1989-1970

Million metric tons (round weight) Billion dollars

Catch Value

1970 2.2 .6 1971 2.3 .7 1972 2.2 .7 1973 2.2 .9 1974 2.3 .9 1975 2.2 1.0 1976 2.4 1.3 1977 2.4 1.5 1978 2.7 1.9 1979 2.8 2.2 1980 2.9 2.2 1981 2.7 2.4 1982 2.9 2.4 1983 2.9 2.4 1984 2.9 2.3 1985 2.8 2.3 1986 2.7 2.8 1987 3.1 3.1 1988 3.3 3,5 1989 3.8 3.2

Source: National Marine Fisheries Service. Does not include weight of mollusk shells. The Food and Agriculture Organization estimates include mollusk shells,

tor in this relative increase in share but not value was the increased supply of imported shrimp. The world supply of shrimp grown in ponds, aquaculture, increased dramatically during the period with negative impacts on prices.

A Supply Role for Aquaculture The data in Table 1 for world catch are inclusive of supplies

from farmed sources. Various species comprise the production from aquaculture. If seaweeds are excluded, the more reliable aquaculture estimates relate to the post1983 period. In 1984 the aquaculture share of world catch (83.9 million MT) was 7.9%. It increased each year until 1989 when the share was 11.2%. By 1989, it was evident that aquaculture production enhanced inland/



Table 5 United States Commercial Landings and Value

of Edible Finfish and Shellfish 1980-1990

169

Million metric tons Billion $

Finfish Shellfish Finfish Shellfish

1980 1.1 .52 1.0 1.1 1981 1.1 .52 1.1 1.2 1982 1.1 .44 1.1 1.2 1983 1.1 .40 1.0 1.2 1984 1.1 .44 1.0 1.2 1985 1.0 .46 1.1 1.1 1986 1.0 .52 1.2 1.4 1987 1.3 .54 1.5 1.5 1988 1.5 .58 1.9 1.5 1989 2.2 .59 1.6 1.5 1990 2.8 .59 1.8 1.6

f reshwater supply the most. Approximately 46% of the supply came from aquacu l tu re while the b rack i sh /mar ine sha re was 5.5%. There was less difference in quant i ty , wi th in land aquaculture supply reaching 6.5 million MT compared to mar ine ' s 4.7 mill ion MT. Atlantic and Pacific salmon, grass carp, f r e shwate r prawns, scallops, and shr imp supplies increased the most from aquacul ture sources.

The Uni ted States ' aquacul ture indus t ry was documented in 1989 to have produced .44 mill ion MT worth $650 mill ion (12). This represents a 300% increase over the 1980 volume. In con- t r a s t to the world s i tuat ion, Uni ted Sta tes supply is res t r ic ted to few species. Seventy percent of supply arises from catf ish farms centered in the South. Other major species and p r imary areas are rainbow trout focused in Idaho, crawfish pr imar i ly in Louisi- ana, oysters from Washington, Louisiana, and Chesapeake Bay, c lams on the Eas t Coast, and a l l igators from Lou i s i ana and Florida. Small quant i t ies of salmon, shrimp, hybr id s t r iped bass, tflapia, and other species are also produced. The outlook is for cont inued growth in aquacu l t u r e origins of seafood r each ing Uni ted Sta tes consumers. Progress toward increased consump- t ion goals by the year 2000 set by indus t ry will necess i ta te a major increase over the i1% contr ibut ion to t989 supp ly by aquacul ture . The production from aquacul ture will br ing wi th it



interest in feed additive residuals, water quality, and fish dis- ease treatment aspects of this supply offish.

Seafood Consumption On a world basis the increase in per capita seafood consump-

tion was not impressive during the 1980s. From an average of 12.3 kg (round weight) consumption increased to 13.1 kg in the decade for an increase of 6.5%. As shown previously, however, in the aggregate, this reflects a substantial quantity of fish and shellfish (Table I). Large increases in supply stress delivery systems by handling larger volumes and dealing with an increasing number of species at perhaps more remote areas. United States per capita consumption increased 39% for the decade to 49.7 kg. Fresh and frozen products accounted for 65% of the total. Canned products, dominated by tuna and salmon items, accounted for 33%. The small remaining amount was related to cured product consumption.

Per capita seafood consumption in the United States proceeded at a record rate in spite of increasing prices. When consumer prices for seafood are based on 1982-1984 = I00, consumers faced a price index of 143.6 in 1989 (13). A similar index kept for ex-vessel prices indicated that producers received prices in 1989 only 9% higher than 1982. That is, the index was i00 in 1982 and only 109 in 1989. However, the exvessel index was as high as 135 in 1988 for the period. The larger increase in the consumer price index may reflect a number of influences, such as increased processing services, higher demand, and willingness to pay for perceived increases in quality.

Processing Approximately 72% of harvested fish and shellfish world

wide are utilized for human food. The remainder is used for animal food or for the manufacture of products for industrial purposes. As previously discussed, hundreds of aquatic species make up the classification of animals that are called seafoods. These include finfish, mollusks, crustaceans, mammals, reptiles, and amphibians. Most of these animals can be harvested from wild stocks and some can be produced from aquaculture. They are con-



sumed in a var ie ty of product forms, inc luding raw, smoked, dried, pickled, salted, cooked, and pasteurized. A few of the more common seafood processing procedures are described below.

Crustaceans Crabs, shr imps, prawns, lobsters, and crawfishes are the

major categories of crustaceans processed for h u m a n food. Crus- taceans are captured in traps (crabs, lobsters, and crawfish) or in nets or t rawls (shr imp and prawns). During the season, t raps are general ly bai ted to at tract crustaceans and are usual ly checked daily. Trawls use no bai t but are set in areas l ikely to harbor the desired crustaceans. Although t radi t ional ly consumed crustaceans are harves ted from wild stocks, aquacul ture production or shr imps, prawns, and crawfishes has become commercial ly significant. Crabs, lobsters, and crawfish are harves ted and mainta ined alive unt i l processing. Shr imps and prawns are harves ted live but die short ly after capture and are iced or frozen at the t ime of processing. Once captured, it is crucial tha t the crustacean be quickly delivered to the processing facility. Crus taceans are par t icular ly susceptible to proteolytic decomposition tha t can resul t in highly undesi rable texture changes. A general overview of the major processing steps of some selected crustaceans are discussed in the following sections.

Cooked Ready-to-Eat

Some crustaceans, such as crabs and crawfish, use blanch= ing as a major processing step. These products are general ly fully cooked and are offered to marke t ing channels as a cooked ready- to-eat product. Because these seafoods may not be reheated to destroy bacteria that mayhave recontaminated the product prior to consumption, they are of great concern to regulatory and health agencies.

Processing Crustaceans There is great var ia t ion in processing procedures for crusta-

ceans. Nearly every form of crustacean processing with the notable exception of shr imp requires manua l hand l ing and processing of the product. Crabmeat and crawfish meat product forms are deli- cate, require careful handl ing, and do not lend themselves to mechanized manipula t ions .

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Crabs

Blue crabs are a common species of crabs caught throughout the Gulf of Mexico and along the Atlantic Coast from Flor ida to New Jersey. These crabs are delivered to processing p lants alive short ly after capture from shallow mar ine bays and estuaries. At the processing facility, crabs may be graded live. The larger crabs are sold to res tauran ts and other commercial markets where they are prepared and consumed as whole, cooked, and seasoned crabs. Smal le r crabs are processed for meat. After wash ing and clean- ing them of extraneous mater ial , they are cooked e i ther by boiling in water or by s teaming in a retort under pressure. In some states, boiling is not permitted. Cooking t imes and tempera tures vary great ly (14). Crabs are known to harbor mar ine pathogenic organisms, and cooking mus t be adequate to destroy these pathogens. Once cooked, the crabs must not be recontamina ted with live crabs or by workers or mater ia ls previously in contact wi th live crabs. A 1979 cholera outbreak in Louisiana was a t t r ibuted to noncommercial crabs being put back into an unsan i t i zed car- ton used to hold the live crabs (15). In Gulf Coast states, the hot crabs are "backed" and washed to remove in ternal organs prior to cooling. Eas t Coast processors general ly do not back or wash crabs prior to cooling and picking. Crabs are re~ igera ted over- n ight to "set" the meat prior to picking. To retard microorganism growth dur ing this period, tempera ture mus t be m a i n t a i n e d to tess t han 40 ~ F (4.4~ However, without adequate air circula- tion, cooling may not be adequate even at these low tempera- tures. Oh et al. (16) compared cooling debacked crabs us ing forced air cooling with static-air cooling. The rate of cooling us ing forced- air cooling was significantly (p < 0.01) faster than stat ic a i r cooling. In addition, bacteria numbers were significantly lower using forced-air cooling. E. coli and S. aureaus counts were fourfold lower and aerolic plate counts and psychrotrophic plate counts were s ignif icant ly lower (p < 0.01). Meat from the cooled crabs is m a n u a l l y removed and packaged.

Although mechanical meat pickers have been used with limited effectiveness over the years, the highest quality meat is still hand- picked meat. Blue crabs yield three basis types of mea t depending on the par t of the body from which it was removed. Claw,

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m e a t is obviously removed from the claws and arms. It is whi te and brown. This is generally considered to be the lowest va lued meat . White or flake mea t is removed from the body segments a t t ached to the walking legs. This mea t is white and is in rela- t ively small pieces~ Of all crabmeat, it may contain the most pieces of shell. The lump or back fin meat is considered the pre- mium grade of blue crabmeat. It is the meat removed from the body segment attached to the swimming appendage. It generally can be removed in one large piece and has few pieces of shell.

The shelf life of fresh crabmeat varies with storage conditions and sanitation of preparation. Generally, fresh crabmeat will have a shelf life of less than i0 d. Other preservation meth- ods can greatly extend the shelf life. Freezing can extend the shelf life for a year. However, there can be noticeable changes in texture, flavor, and color in frozen crabmeat. Crabmeat can be heat pasteurized in hermetically sealed cans to extend the shelf life 6-8 too. Pasteurized crabmeat is like fresh meat and is considered to be an important commercial product. Pasteurization is an exacting process and recommended procedures must be followed carefully. Since pasteurized crabmeat is not sterile, refrigerated storage conditions are essential for maximum shelf life.

Food additives are sometimes used in pasteurized crabmeat to prevent discoloration or struvite formation. Struvite in crabmeat is manifested by the formation of small magnesium crystals after several months of storage.

Other types of domestically processed crabs include King crab, Dungeness crab, Jonas crab, Stone crab, and Deep Sea Red crabs. Many of these species make up only a small portion of the commercial market. Processing generally includes some type of heat treatment before introduction into commercial market channels. Ward gives a good overview of King crab handling and processing (14).

Shrimp Shr imp are perhaps the best known crustaceans to consum-

ers in the Uni ted States. As a commercial fishery, shr imp are world wide. When captured from wild stocks, boats pulling t rawls are generally used. Shrimp from aquaculture are harvested using nets or draining the growing pond. Proper handling of shrimp after capture is extremely important for quality. Shrimp may be

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headed and graded at sea. Because shrimp die shortly after harvesting, they must be iced or frozen quickly to minimize decomposition. Black spot is an economically important defect. This undesirable condition is caused by a combination of factors, including light, oxygen, and natural components in the shrimp. In order to prevent black spoL freshly caught shrimp should be washed thor- oughly before icing or freezing. It is also a common practice to treat shrimp with an aqueous solution of sodium bisulfite. Because of allergic reactions experienced by a small percentage of the population, great care must be used when treating shrimp with this compound. Food and Drug Administration laws regulate the amount and usage of this compound in shrimp.

Shrimp processing is highly automated when compared to other types of seafood processing. When unloaded at processing plant docks the shrimp are deiced in water and graded on auto- matic and very accurate mechanical graders. One of the more important commercial product forms is frozen, headed raw shrimp. Although the head (cepha]othorax) is removed, the shell on the tail meat is not removed. Traditionally, this product is hand packed into boxes designed to hold 5 pounds, mechanically frozen (plate or blast frozen), and glazed with ice. Glazing pre- vents dehydration (freezer burn).

Frozen, peeled, and deveined shrimp is also a product of significant commercial importance. All shells and veins are mechanically removed the product. Peeled and deveined shrimp may be individually-quick-frozen (IQF) and packaged or frozen in a pouch. Frozen, raw shrimp products may be treated with sodium tripolyphphate to retain a succlent texture and to minimize dehydration.

Other less significant shrimp products include canned shrimp and dried shrimp. Both products use smaller, less valu- able shrimp. Canning uses peeled shrimp packed in brine. Com- mercial dried shrimp in the United States is restricted almost exclusively to a few processing plants in south Louisiana. Mechani- cal indoor driers have replaced the weather-dependent sun drying platform of years gone by. The mechanical driers use temperature-controlled, forced air systems to consistently dry the product.

Clinical Reviews in Allergy Volume 1 I, 1993


Crawfish

Crawfish production and processing is commercially important in the United States, primarily in Louisiana and adjacent states. There is some production in the Pacific Northwest and California. Like crabs, crawfish are harvested using baited traps. Aquaculture of crawfish is becoming increasingly important. A significant portion of the commercial harvest comes from aquaculture activities. After harvesting, crawfish are tightly packed into mesh sacks for storage until processing. In order to main- tain crawfish alive, they are kept cool, in high humidity to prevent dehydration, and in low volume circulating air to prevent suffocation. Moody provides an excellent review of crawfish processing procedures (17). Preparation of the crawfish for processing includes the steps of grading and washing. Mechanical devices generally separate live crawfish into three sizes. The largest crawfish are prepared for whole, boiled, and seasoned product. A significant percentage of this product is exported to international markets, especially to Scandinavia. Much of the medium sized crawfish are targeted to whole, live local markets or peeled for meat. Small crawfish are generally peeled for meat. Live crawfish are washed by immersing in a vat of clean, potable water. A belt at the bottom of the vat automatically removes the crawfish from the water onto a moving inspection belt. During washing, extraneous debris and bait are removed. Crawfish are heat processed immediately after washing. Cooking baskets are loaded with crawfish by the moving inspection belt and placed into boiling water for processing. Cooking time is critical to proper heat treatment. Overcooking produces an undesirable product that is difficult to hand peel. Undercooking, on the other hand, may result in a highly undesirable mushy meat texture. This mushiness result- ing from undercooking is a t t r ibuted to proteolytic enzymes. Marshall et al. studied the effects of blanch time and crawfish meat texture (18). Whole, cooked crawfish are hand peeled for meat while still warm from cooking. Meat yield is approx 15%. Workers peel meat directly into sanitized colanders. Full colanders are delivered to a separate packing room for packaging. Fresh meat is packaged into polyethyene bags containing one pound or 12 ounces of meat. Meat to be frozen is generally put

Clinical Reviews in Allergy Volume 11, t993

I76 Moody, Roberts, and Huner

into laminated bags to prevent dehydration. Fresh meat is normally packaged with the edible hepatopancreas. Meat to be frozen may be packed with or without hepatopancreas. This material may become rancid during frozen storage. Steps can be taken to re tard or minimize the on set of rancidity. After packaging, the bagged crawfish m e a t is chilled in an ice slush prior to fresh s torage or freezing. Fresh crawfish meat has a shelf life of 7-10 d. Frozen crawfish mea t has a frozen shelf life of 3-8 too, depending on the stability of the hepatopancreas. Whole, frozen crawfish is generally packed in t rays wi th seasoned liquid and frozen cryogenically.

Processing Mollusks The most common mollusk consumed in the Uni ted Sta tes

are the bivalve molluscan shellfish. The most common are oysters, clams, and mussles. One of the outs tanding requ i rements of commercial mollusk production is the harves t ing and handl ing regulat ions. It mus t be assumed tha t all aquatic bivalve mollusks will be consumed raw. Consequently, wa te r over the beds t h a t the shellfish are harvested is carefully and strictly monitored for fecal contaminat ion through prescribed sampling techniques and t ime intervals. Molluscan shellfish are of major public hea l th concern. The In te rs ta te Shellfish Sani ta t ion Conference (ISSC) is t a sked with the responsibili ty of overseeing and monitor ing molluscan shellfish harves t ing and processing. This body is made up of representa t ives from the Uni ted States Food and Drug Admin- is trat ion, s ta te regulatory and patrol agencies, and indus t ry representa t ives .

Mollusks are harves ted live from designated wa te r bottoms called beds and t ranspor ted to storage areas using re f r igera ted t rucks. Harves te r s wash sediments and other foreign ma te r i a l from the shellfish prior to discharging from boats and sack or box the clean clam shellfish. Harves te r s are also required to properly tag or label each container or sack of shellfish to a t t es t to proper ha rves t ing requirements and location. Under proper holding conditions, mollusks can be main ta ined alive for an extended period of time. Holding facilities m a y be wet s torage where the shellf ish are placed in approved tanks of water. Wet storage is used primari ly to remove sand or to improve the sal t content of the shellf ish meat . Wet storage facilities mus t be constructed and opera ted



under strict Federal and state regulations. Some shel l f ish may be held in dry storage. Generally, these facilities are located at processing plants. In order to ma in t a in the shel l f ish alive and to min imize microbiological contaminat ion or growth, dry storage areas mus t be properly refrigerated and sanitized.

The two most significant product forms for molluscan shell- f ish are (1) whole, live and (2) shucked. Whole, live shel l f ish are shipped directly to retail and wholesale dealers and users pr ima- r i ly for the ha l f shell market . Shucked shel lf ish are prepared at processing facilit ies for the j a r or gallon trade. Many times, but cer ta inly not always, shucked shellf ish are cooked prior to consumption. Shellf ish processing plants must meet all of the hea l th requi rements of other seafood processing plants. In the case of oyster processing, workers shuck live oyster meats into buckets. The shell is discarded as waste and removed from the plant. The buckets of oyster meats are delivered to the packing room where the meats are gently washed and inspected to remove pieces of shell and foreign mater ial . The meats are packed into containers of various sizes, depending on the market , iced, and shipped. Oys- ters can be sold by volume, gallon, quart, or pint~ Oysters may be frozen~ Other shellfish, such as clams and scallops, are processed s imi la r to oysters~ Clam meats may be chopped, diced, or sliced for the chowder market or for strips. The abductor muscle is the only edible scallop portion. Canning of oysters and clams is done on a l imited scale.

The consumption of raw molluscan shel lf ish is a s ignif icant concern for regulatory agencies. The microbiological monitor ing of harves t ing water using indicator organisms is effective for the prevention of enteric viral and bacteriological infection; however, this technique is of no value for indigenous pathogenic bacter ia such as Vibrio vulnificus or Vibrio cholera. A majori ty of the shel l f ish producing areas are closed to harves t ing because of fecal contaminat ion. In order to increase shellf ish safety, there are several technologies that have been offered tha t would cleanse the living shellfish or eliminate pathogens without changing the desir- able characterist ics of the raw meat. Depurat ion of shel l f ish has been used throughout the world as a method of f lushing fecal contaminates from oysters and clams. Depurat ion is dependent on the living shellfish to pump water through its tissues to remove

Clinical Reviews in Allergy Volume 1 I, 1993


contaminates . Shellf ish are place into tanks of purified water for a predetermined period of time followed by microbiological testing for effectiveness..During the deputation period, the water is sanitized using ozone and/or ultraviolet light. Depuration is effective for removing fecal contaminates including viruses. A var ia t ion of depuration is called relaying. Shellfish, usual ly oysters, are relayed by transplant ing them from one natural area of moderately polluted water to another na tura l area of nonpolluted water. Relaying requires considerable more time, usual ly weeks, for the shel l f ish to be c leansed of con tamina tes . The ind igenous pa thogens , Vibiros, are not removed by depurat ing or relaying. I r radiat ion of shel l f ish us ing a radioactive source is current ly being evalu- ated for effectiveness as a method for e l imina t ing these pathogens from shellfish.

Process ing F in f i sh

There are numerous species and product forms of finfish. F inf i sh are harves ted from fresh, salt, or es tuar ine waters. They are from wild stocks or from aquaculture. Fish are captured using a var ie ty of techniques, including nets, trawls, traps, or hooks. Fish die soon after capture and must be immedia te ly chilled or frozen, since they are susceptible to rapid decomposition. From capture boats, the fish are unloaded at processing plants or t ranspor ted from docks to processing plants or end users. In the case of aquaculture grown fish, the fish may be trucked alive directly from growing ponds to processing plants. A truck equipped wi th water tanks and an oxygenation apparatus is used for this purpose. At the processing plant, fish may be processed into numerous product forms. The most common are fresh, frozen, canned, dried, and smoked.

Fresh fish and frozen fish products are the most common product forms. Most species of fish are available in one of these two forms. These uncooked portions are generally marketed as whole and drawn, dressed, steaks, fillets, or nuggets, depending on the type of cut. In addition, the meat may be skinless or bone- less. Finfish processing plants vary in technology levels. Some depend almost entirely on manual butchering. Modern high technology finfish processing plants are almost entirely automated. These plants have equipment that is capable of performing nearly all processing steps including evisceration, heading, skinning,



filleting, grading, and t r imming to exact portion control. Cryo- genic technology is general ly used to freeze the fish products. Few food addit ives are used in the processing of fresh or frozen f ish wi th the exception of phosphates to protect the product during freezing and storage.

Only a few species of fish are suitable for canning. Oil content of the fish, texture, flavor and t radi t ion are some of the factors tha t mus t be considered for fish canning. There are m a n y product forms for canned fish. Canned fish may be processed with or without the bones and sMn. In some species, f ish are cooked prior to being sealed in cans. In other cases, raw fish is placed in cans prior to processing. Canned fish may be packed in water, oil, sauces, or broth. Since canned fish is considered to be a low acid food, it mus t retort processing using specified t imes and tempera ture to ensure commercial sterility.

In the Uni ted States, dried, salted, or smoked fish make up only a smal l portion of the commercial finfish market . These products are br ined for taste and some preservation, dried, or smoked. The two most common smoking techniques are (1) hot smoMng and (2) cold smoking. Hot smoking is a succulent product tha t has achieved a relat ively high cooking tempera ture and cooked for a specified period of time. Cold smoking, on the other hand , is processed at a lower temperature for a longer period of t ime. Cold smoked fish are not as succulent as hot smoked fish. The refrigerated storage of smoked fish is extremely critical. Mishand l ing or improper tempera tures of smoked fish dur ing storage could resul t in the growth of Clostridium botulinum. Moody and Flick provide a more detai led description of dried, salted, or smoked fish processing (19).

HACCP Sani ta t ion and safety of seafood products is becoming more

impor tan t to consumers, regulatory agencies, and the industry. Although there are reguiat ions that require tha t all seafood processing plants in the United States meet m i n i m u m sani ta t ion s tandards for processing h u m a n foods, there is no manda to ry inspection program as there is for red meats and poul t ry products. Various federal regulatory agencies have offered proposals for such a manda ted seafood inspection program~ The under ly ing

Clinical Reviews in Allergy Volume 1 t, 1993


pr inc ip le of t hese proposals is t he Haza rd Analys is Cri t ical Con- trol Po in t (HACCP) concept. Us ing this concept, process ing p lan t s a n d o the r s e g m e n t s of t he i n d u s t r y involved in the h a n d l i n g of seafoods would be r equ i r ed to careful ly mon i to r all p rocess ing s teps w h e r e safety, hea l th , or economic r i sk could occur if no t p roper ly controlled. HACCP requ i res record k e e p i n g of t he process ing and h a n d l i n g steps. C o m p u t e r technology is p lay ing a key role in controlling and monitoring of product refrigeration and in the controlling of critical processing steps such as pas- teurizing, blanching, retorting, smoking, and cooking reformed seafood products. Computers will continue to be important in the establishment of processes and in processing problem solving.

References 1. Seafood Leader (1990), Seafood Leader 10(2), p. 336. 2o Straus, K. (1989), Seafood Handbook '89 Selling Seafood. Seafood Busi-

ness, Rockland, MA, p. 216. 3. Lagler, K. F., Bardach, J. E., and Miller, R. R. (1967), Ichthyology. Wiley,

New York, p. 545. 4. Walls, J. G. (1975), Fishes of the Northern Gulf of Mexico. TFH Publica-

tions, Neptune City, NJ, p. 432. 5. Barnes, R. D. (1986), Invertebrate Zoology (2nd ed.), Saunders, Philadel-

phia, p. 743. 6. National Marine Fisheries Service (1991), Fisheries of the United States,

1990, United States Department of Commerce, Silver Springs, MD, p. 113. 7. National Marine Fisheries Service (1991), Frozen Fishery Products 1990,

Silver Springs, MD, p. 4. 8. National Marine Fisheries Service (1989), Processed Fishery Products 1988,

Silver Springs, MD, p. 23. 9. National Marine Fisheries Service (1992), Imports and Exports of Fishery

Products 1991, Silver Springs, MD, p. 17. 10. Food and Agriculture Organization (1990), Fishery Statistics Catches and

Landings Yearbook 1989, United Nations, Rome, Italy, p. 490. 11. Bell, F. W. (1978), Food from the Sea: The Economics and Politics of Ocean

Fisheries, Westview Press, Boulder, CO, p. 380. 12. New, M. B. (1991), World Aquaculture 22(3)~ World Aquaculture Society.

Baton Rouge, LA, pp. 28-49~ 13. United States Department of Agriculture (1991), Economic Research Ser-

vice, Washington, DC, p. 20. 14. Ward, D. R. (1990) The Seafood Industry (Martin, R. E. and Flick, G. J.,

eds.), Van Nostrand Reinhold, New York, pp. 174-181. 15. Moody, M. W. (1979), Proceedings of the Blue Crab Colloquium, Gulf States

Marine Fisheries Commission, pp. 65-69.



16. Oh, D., Marshall, D. L., Moody, M. W., and Bankston, J. D. (1992), J. Food Prot. 55, 104.

17. Moody, M. W. (1989), J. Shellfish Res., 8~ 293. 18. Marshall, G. A., Moody, M. W., Hackney, C. R., and Godber, J. S. (1987), J.

Food Sci., 527 1500. 19. Moody, M. W. and Flick, G. J. (1990), The Seafood Industry (Martin, R. E.

and Flick, G. J., eds.), Van Nostrand Reinhold, New York, pp. 381-406.


Documents

Phytogeny of commercially important seafood and description of the seafood industry