Fish Grams/ounce
Rainbow trout 0.30
Lake whitefish 0.25
Source: “Food for the Heart,” American Health, April 1985.
Fish oils are one of the few natural food sources of vitamin D. Salmon also has vita-min A derived from carotenoid pigments in the plants eaten by the fish. The soft bones in some canned salmon and sardines are an excellent source of calcium. CAUTION: do not eatthe bonesin rawor cookedfish. the only bonesconsiderededible arethose inthe cannedproducts.
The Most Nutritious Way to Serve This Food
Cooked, to kill parasites and potentially pathological microorganisms living in raw fish.
Broiled, to liquify fat and eliminate the fat-soluble environmental contaminants found in some freshwater fish.
With the soft, mashed, calcium-rich bones (in canned salmon and canned sardines).
Diets That May Restrict or Exclude This Food
Low-purine (antigout) diet
Low-sodium diet (canned, salted, or smoked fish)
Buying This Food
Look for: Fresh-smelling whole fish with shiny skin; reddish pink, moist gills; and clear, bulging eyes. The flesh should spring back when you press it lightly.
Choose fish fillets that look moist, not dry.
Choose tightly sealed, solidly frozen packages of frozen fish.
In 1998, the FDA/National Center for Toxicological Research released for testing an inexpensive indicator called “Fresh Tag.” The indicator, to be packed with seafood, changes color if the product spoils.
Avoid: Fresh whole fish whose eyes have sunk into the head (a clear sign of aging); fillets that look dry; and packages of frozen fish that are stained (whatever leaked on the package may have seeped through onto the fish) or are coated with ice crystals (the package may have defrosted and been refrozen).
Storing This Food
Remove fish from plastic wrap as soon as you get it home. Plastic keeps out air, encouraging the growth of bacteria that make the fish smell bad. If the fish smells bad when you open the package, throw it out.
Refrigerate all fresh and smoked fish immediately. Fish spoils quickly because it has a high proportion of polyunsaturated fatty acids (which pick up oxygen much more easily than saturated or monounsaturated fatty acids). Refrigeration also slows the action of microorgan-isms on the surface of the fish that convert proteins and other substances to mucopolysac-charides, leaving a slimy film on the fish.
Keep fish frozen until you are ready to use it.
Store canned fish in a cool cabinet or in a refrigerator (but not the freezer). The cooler the temperature, the longer the shelf life.
Preparing This Food
Fresh fish. Rub the fish with lemon juice, then rinse it under cold running water. The lemon juice (an acid) will convert the nitrogen compounds that make fish smell “fishy” to compounds that break apart easily and can be rinsed off the fish with cool running water.
Rinsing your hands in lemon juice and water will get rid of the fishy smell after you have been preparing fresh fish.
Frozen fish. Defrost plain frozen fish in the refrigerator or under cold running water. Pre-pared frozen fish dishes should not be thawed before you cook them since defrosting will make the sauce or coating soggy.
Salted dried fish. Salted dried fish should be soaked to remove the salt. How long you have to soak the fish depends on how much salt was added in processing. A reasonable average for salt cod, mackerel, haddock (finnan haddie), or herring is three to six hours, with two or three changes of water.
When you are done, clean all utensils thoroughly with hot soap and hot water. Wash your cutting board, wood or plastic, with hot water, soap, and a bleach-and-water solution.
For ultimate safety in preventing the transfer of microorganisms from the raw fish to other foods, keep one cutting board exclusively for raw fish, meats, and poultry, and a second one for everything else. Finally, don’t forget to wash your hands.
What Happens When You Cook This Food
Heat changes the structure of proteins. It denatures the protein molecules so that they break apart into smaller fragments or change shape or clump together. These changes force moisture out of the tissues so that the fish turns opaque. The longer you cook fish, the more Fish
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moisture it will lose. Cooked fish flakes because the connective tissue in fish “melts” at a relatively low temperature.
Heating fish thoroughly destroys parasites and microorganisms that live in raw fish, making the fish safer to eat.
How Other Kinds of Processing Affect This Food
Marinating. Like heat, acids coagulate the proteins in fish, squeezing out moisture. Fish marinated in citrus juices and other acids such as vinegar or wine has a firm texture and looks cooked, but the acid bath may not inactivate parasites in the fish.
Canning. Fish is naturally low in sodium, but canned fish often contains enough added salt to make it a high-sodium food. A 3.5-ounce serving of baked, fresh red salmon, for example, has 55 mg sodium, while an equal serving of regular canned salmon has 443 mg.
If the fish is canned in oil it is also much higher in calories than fresh fish.
Freezing. When fish is frozen, ice crystals form in the flesh and tear its cells so that mois-ture leaks out when the fish is defrosted. Commercial flash-freezing offers some protec-tion by freezing the fish so fast that the ice crystals stay small and do less damage, but all defrosted fish tastes drier and less palatable than fresh fish. Freezing slows but does not stop the oxidation of fats that causes fish to deteriorate.
Curing. Fish can be cured (preserved) by smoking, drying, salting, or pickling, all of which coagulate the muscle tissue and prevent microorganisms from growing. Each method has its own particular drawbacks. Smoking adds potentially carcinogenic chemicals. Drying reduces the water content, concentrates the solids and nutrients, increases the calories per ounce, and raises the amount of sodium.
Medical Uses and/or Benefits
Protection against cardiovascular disease. The most important fats in fish are the poly-unsaturated acids known as omega-3s. These fatty acids appear to work their way into heart cells where they seem to help stabilize the heart muscle and prevent potentially fatal arrhythmia (irregular heartbeat). Among 85,000 women in the long-running Nurses’
Health Study, those who ate fatty fish at least five times a week were nearly 50 percent less likely to die from heart disease than those who ate fish less frequently. Similar results appeared in men in the equally long-running Physicians’ Health Study. Some studies suggest that people may get similar benefits from omega-3 capsules. Researchers at the Consorzio Mario Negri Sud in Santa Maria Imbaro (Italy) say that men given a one-gram fish oil capsule once a day have a risk of sudden death 42 percent lower than men given placebos (“look-alike” pills with no fish oil). However, most nutrition scientists recom-mend food over supplements.