In discussing the food uses of fishes, the term 'fish' refers to edible species of finfish, molluscs, and crustacea coming from the marine or freshwater bodies of the world, either by capture fisheries or by aquaculture. Accordingly, ''fishery products'' means any human food product in which fish is a characterizing ingredient, such as dried, salted, and smoked fish, marinated fish, canned seafood, minced fish flesh such as surimi, and miscellaneous products.
Fish is a source of high-quality animal protein, supplying approximately 6% of the world's protein requirements and 16.4% of the total animal protein. According to Food and Agriculture Organization figures, the contribution of fish to the total animal-protein intake is 26.2% in Asia, 17.4% in Africa, 9.2% in Europe, 9% in the former USSR, 8.8% in Oceania, 7.4% in North and Central America, 7.2% in South America, and 21.8% in the low-income food-deficit countries (including China). There are wide differences among countries in fish consumption measured as the average yearly intake per person, ranging from countries with less than 1.0 kg per person to countries with over 100 kg per person.
Edible fish muscle contains 18-20% protein and 1-2% ash; the percentage of lipids varies from less than 1% to more than 20% (in high-fat finfish), and fish has the added advantage of being low in saturated fat. In general, lean fish is not an important source of calories, which are mostly obtained from the staple carbohydrates in the diet. Fatty fish, however, is a significant energy source in many fish-consuming communities in both the developed and the developing worlds. Today it is recognized that fish is probably more important as a source of micronutrients, minerals, and particularly essential fatty acids than for its energy or protein value. The essential micro-nutrients and minerals in fish include vitamins A and D, calcium, phosphorus, magnesium, iron, zinc, selenium, fluorine, and iodine (in marine fishes).
The protective effect of a small amount of fish against mortality from coronary heart disease (CHD) has been established by numerous epidemio-logical studies. A diet including two or three servings of fish per week has been recommended on this basis, and researchers have reported a 50% reduction in CHD mortality after 20 years with intakes of as little as 400 g of fish per week.
It has been suggested that the long-chain omega-3 (n-3) polyunsaturated fatty acids (PUFAs) (eicosapen-tanoic acid (EPA; C20:5) and docosahexanoic acid (DHA; C22:6)) in fish offer this protection against CHD. Several recent studies have shown that a large intake of omega-3 fatty acids is beneficial in lowering blood pressure, reducing triacylglycerols, decreasing the risk of arrhythmia, and lowering the tendency of blood platelets to aggregate.
As fish become more popular, the reports of food-borne diseases attributed to fish have increased. Food-borne diseases linked with exposure to fish can result from the fish itself (i.e., toxic species, allergies) or from bacterial (i.e., Clostridium botuli-num, Listeria monocytogenes, Salmonella, Vibrio, and Staphylococcus), viral (i.e., hepatitis, Norwalk gastroenteritis), or parasitic (i.e., Anisakis and related worms) contamination. Also, naturally occurring seafood toxins (i.e., scombrotoxin, cigua-toxins, shellfish poisoning from toxic algae) or the presence of additives and chemical residues due to environmental contamination can cause food-borne illnesses. In recent years, reports of contamination of some fish with methylmercury have raised concerns about the healthfulness of certain fish for some populations.
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