Fish white-fleshed

Chowder is a thick soup or stew of seafood (like clams or white-fleshed sea fishes), usually made with milk and containing salt pork or bacon, onions, potatoes, and sometimes other vegetables. 

Sediments and biota collected from the Hersey River, Michigan, in 1978, were heavily contaminated with phenanthrene, benz[a]anthracene, and benzo[a]pyrene when compared to a control site. Elevated PAH concentrations were recorded in sediments, whole insect larvae, crayfish muscle, and flesh of lampreys (family Petromyzontidae), brown trout (Salmo trutta), and white suckers (Catostomus commersoni), in that general order (Black et al. 1981). The polluted collection locale was the former site of a creosote wood preservation facility between 1902 and 1949, and, at the time of the study, received Reed City wastewater treatment plant effluent, described as an oily material with a naphthalene-like odor (Black et al. 1981). In San Francisco Bay, elevated PAH concentrations in fish livers reflected elevated sediment PAH concentrations (Stehr et al. 1997). In Chesapeake Bay, spot (Leiostomus xanthurus) collected from a PAH-contaminated tributary (up to 96 mg PAHs/kg DW sediment) had elevated cytochrome P-450 and EROD activity in liver and intestine microsomes (Van Veld et al. 1990). Intestinal P-450 activity was 80 to 100 times higher in fish from highly contaminated sites than in conspecifics from reference sites intestinal EROD activity had a similar trend. Liver P-450 and EROD activity was about 8 times higher in spot from the contaminated sites when compared to the reference sites. Liver P-450 activity correlated positively with sediment PAH, but intestinal P-450 activity seemed to reflect dietary exposure (Van Veld et al. 1990). The poor correlation between hepatic concentrations of PAHs and P-4501A is attributed to the rapid metabolism of these compounds (van der Weiden et al. 1994). 

Muravskaya, 1978 Diana and Mackay, 1979 Shatunovsky, 1980). However, in all starved fish it is the lipid that is mobilized first, except possibly in the eel. In fatty fish, much lipid is used from the flesh, while in lean fish it is used from the liver. In both types of fish, muscle protein is mobilized only when the lipid resources fall below a critical level. Black and Love (1986) showed that energy substrates are mobilized in a definite sequence, white muscle protein, for example, being metabolized at an earlier stage than red muscle protein, while, on refeeding, the latter is replenished before the former. 

J. N. Cobb discusses the kippering of salmon as follows On the Pacific coast practically all of the kippered salmon is prepared from frozen white-meated king salmon, which on account of the color of the flesh is not in much demand. It is, however, fully the equal, in both flavor and food value, of the red-meated kinds. It is not absolutely essential that the fish be first frozen, as the fresh fish may be kippered after dressing, but the latter is always a little soft when so prepared owing to an excess of moisture, which is largely removed in freezing. Fresh salmon is available only part of the year, so it is found most convenient to freeze and store the stock and work it up when needed throughout the year. 

The fact that certain fish species (eg. snallmouth bass) in Cranberry Lake exhibit disproportionately high levels of mercury in their flesh when compared to other species (eg. white sucker), is probably related to the fish s status in the food chain. 

In the traditional process for fish surimi production, the fish flesh is washed on large screens and the oil is washed through the screens. This process is suitable for the separation of the liquid oil from fish however, solid fats (such as occur in red meat) would not separate in this way but would remain on the screens with the water-insoluble proteins. Red meat also contains higher levels of fat than white fish. Fat separation from meat is therefore more difficult than from fish. Separation can be carried out using flotation and skimming however, this introduces further steps into the process and increases processing times. 

The protein in fish is denatured by the low pH of lime juice. Notice that the flesh shown with the limes has turned white compared with the flesh at normal pH. 

Products with extended shelf lives are in their own juice or in added oil, or in some sauce or cream (e. g. sardine pilchards, Sardina pilchardus, packed in olive or soya oil, tomato mustard, or lemon juice). Also available are fish paste, meat balls or Frikadellen (Germany), i. e. flesh of white fish made into rissoles using flour, eggs and spices, which are then roasted, deep fried and used ready-to-serve, as hors d oeuvres, and fish salad. The latter products are canned or packed in glass jars, and may be packed under controlled atmosphere. 

These fishes have fat in their flesh, which is usually much darker than that of white fishes, with similar blocks of muscle and connective tissue. The amount of fat is related to the breeding cycle of the fish, so that the fat content falls considerably after breeding. The flesh of fatty fishes is generally richer in the B vitamins than that of white fishes, and significant amounts of vitamins A and D are present. The mineral concentrations are not very different, but fatty fish is a better source of iron. The oil of these fishes is particularly rich in very-long-chain PUFA, especially those of the omega-3 ( -3) series such as EPA and DHA. These fishes accumulate oils in their muscles, belly flap, and skin (subdermal fat). 

The cartilaginous fishes include the sharks and rays, whose flesh is rich in connective tissue and relatively low in fat, although they do accumulate oils in their livers. The concentrations of vitamins and minerals are very similar to those in white fish. These fishes contain urea in relatively large amounts, and so protein values based on total nitrogen are overestimated. The ammonia smell of cooked sharks and rays is not an indication that the fish is spoiled but rather is the result of enzymatic degradation of urea. 

In fish, depot fat is liquid at room temperature (oil) and is seldom visible to the consumer an exception is the belly flaps of salmon steaks. Many species of finfish and almost all shellfish contain less than 2.5% total fat, and less than 20% of the total calories come from fat. Almost all fish has less than 10% total fat, and even the fattiest fish, such as herring, mackerel, and salmon, contains no more than 20% fat (Table 1). In order to obtain a good general idea of the fat contents of most finfish species, flesh color might be considered. The leanest species, such as cod and flounder, have a white or lighter color, while fattier fishes, such as salmon, herring, and mackerel, have a much darker color. 

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