Crustaceans ++++ ++++.

Source TMA: fishy TMA: fishy Bromophenol: sea-air Bromophenol: sea-air

Terrestrial meats

Freshwater fish

Salt.w.a.ter fish +++ +++.

Sharks and rays +++ +++.

Molluscs ++ ++.

Crustaceans + +.

Source Ammonia (from urea) Ammonia (from urea) Geosmin, borneol: muddy Geosmin, borneol: muddy

Terrestrial meats

Freshwater fish

Salt.w.a.ter fish

Sharks and rays +++ +++.

Molluscs

Crustaceans

Fish Color Pale Translucence Most of the muscle in most raw fish is white or off-white and delicately translucent compared to raw beef or pork, whose cells are surrounded by more light-scattering connective tissue and fat cells. Especially fatty portions of fish, such as salmon and tuna bellies, look distinctly milky compared to flesh from just a few inches away. The translucence of fish muscle is turned into opacity by cooking treatments that cause the muscle proteins to unfold and bond to each other into large, light-scattering ma.s.ses. Both heat and marination in acid unfold proteins and turn fish flesh opaque. Most of the muscle in most raw fish is white or off-white and delicately translucent compared to raw beef or pork, whose cells are surrounded by more light-scattering connective tissue and fat cells. Especially fatty portions of fish, such as salmon and tuna bellies, look distinctly milky compared to flesh from just a few inches away. The translucence of fish muscle is turned into opacity by cooking treatments that cause the muscle proteins to unfold and bond to each other into large, light-scattering ma.s.ses. Both heat and marination in acid unfold proteins and turn fish flesh opaque.

Red Tunas The meaty color of certain tunas is caused by the oxygen-storing pigment myoglobin (p. 132), which these fish need for their nonstop, high-velocity life (p. 201). Fish myoglobin is especially p.r.o.ne to being oxidized to brownish metmyoglobin, especially at freezer temperatures down to 22F/30C; tuna must be frozen well below this to keep its color. During cooking, fish myoglobins denature and turn gray-brown at around the same temperature as beef myoglobin, between 140 and 160F/60 and 70C. Because they are often present in small quant.i.ties, their color change can be masked by the general milkiness caused when all the other cell proteins unfold and bond to each other. This is why fish with distinctly pink raw flesh (albacore tuna, mahimahi) will turn as white as any white fish when cooked. The meaty color of certain tunas is caused by the oxygen-storing pigment myoglobin (p. 132), which these fish need for their nonstop, high-velocity life (p. 201). Fish myoglobin is especially p.r.o.ne to being oxidized to brownish metmyoglobin, especially at freezer temperatures down to 22F/30C; tuna must be frozen well below this to keep its color. During cooking, fish myoglobins denature and turn gray-brown at around the same temperature as beef myoglobin, between 140 and 160F/60 and 70C. Because they are often present in small quant.i.ties, their color change can be masked by the general milkiness caused when all the other cell proteins unfold and bond to each other. This is why fish with distinctly pink raw flesh (albacore tuna, mahimahi) will turn as white as any white fish when cooked.

Orange-Pink Salmons and Trouts The characteristic color of the salmons is due to a chemical relative of the carotene pigment that colors carrots. This compound, astaxanthin, comes from the salmons' small crustacean prey, which create it from the beta-carotene they obtain from algae. Many fish store astaxanthin in their skin and ovaries, but only the salmon family stores it in muscle. Because farmed salmon and trout don't have access to the wild crustaceans, they have paler flesh unless their feed is supplemented (usually with crustacean sh.e.l.l by-products or an industrially produced carotenoid called canthaxanthin). The characteristic color of the salmons is due to a chemical relative of the carotene pigment that colors carrots. This compound, astaxanthin, comes from the salmons' small crustacean prey, which create it from the beta-carotene they obtain from algae. Many fish store astaxanthin in their skin and ovaries, but only the salmon family stores it in muscle. Because farmed salmon and trout don't have access to the wild crustaceans, they have paler flesh unless their feed is supplemented (usually with crustacean sh.e.l.l by-products or an industrially produced carotenoid called canthaxanthin).

The Fish We Eat The number of different kinds of fish in the world is staggering. Of all the animals that have backbones, fish account for more than half, something approaching 29,000 species. Our species regularly eats hundreds of these. Perhaps two dozen are at least occasionally available in U.S. supermarkets, and another several dozen in upscale and ethnic restaurants, often under a variety of names. The box beginning on p. 195 surveys the family relations of some commonly eaten fish, and the paragraphs that follow provide a few details about the more important families.

Sh.e.l.lfish are also a diverse group of animals. They lack backbones and differ from finfish in important ways, so they're described separately, p. 218.

The Herring Family: Anchovy, Sardine, Sprat, Shad The herring family is an ancient, successful, and highly productive one, and for centuries was the animal food on which much of northern Europe subsisted. Its various species school throughout the world's oceans in large, easily netted numbers and are relatively small, often just a few inches long but sometimes reaching 16 in/40 cm and 1.5 lb/0.75 kg.

Members of the herring family feed by constantly swimming and straining tiny zooplankton from the seawater. They thus have very active muscle and digestive enzymes that can soften their flesh and generate strong flavors soon after they're harvested. Their high fat content, upwards of 20% as they approach sp.a.w.ning, also makes them vulnerable to the off-flavors of easily oxidized polyunsaturated fats. Thanks to this fragility most of these fish are preserved by smoking, salting, or canning.

Names and Family Relations of Commonly Eaten FishesClosely related families are grouped together, and neighboring groups in the chart are more closely related than widely separated groups. Salt.w.a.ter families are listed without special indication; "f" means a freshwater family and "f&s" a family that includes both freshwater and salt.w.a.ter species.

Family Number of Species Number of Species

Examples Examples

Shark (several)

350 350.

Blue ( Blue (Prionace), thresher (Alopias), hammerhead (Sphyrna), black-tipped (Carcharinchus), dogfish (Squalus), porbeagle (Lamna), smooth hound (Mustelus)

Skate

200 200.

Skates ( Skates (Raja)

Ray

50 50.

Rays ( Rays (Dasyatis, Myliobatis)

Sturgeon

24 24.

Beluga, kaluga ( Beluga, kaluga (Huso); osetra, sevruga, Atlantic, lake, green, white (all Acipenser Acipenser)

Paddlefish (f)

2 2.

American, Chinese paddlefish ( American, Chinese paddlefish (Polyodon, Psephurus)

Gar

7 7.

Gar ( Gar (Lepisosteus)

Tarpon

2 2.

Tarpon ( Tarpon (Tarpon)

Bonefish