COMPOSITION AND FOOD VALUE OF FISH
COMPOSITION OF FISH
5. COMPARISON OF FISH WITH MEAT.--In general, the composition of fish is similar to that of meat, for both of them are high-protein foods. However, some varieties of fish contain large quantities of fat and others contain very little of this substance, so the food value of the different kinds varies greatly. As in the case of meat, fish is lacking in carbohydrate. Because of the close similarity between these two foods, fish is a very desirable substitute for meat. In fact, fish is in some respects a better food than meat, but it cannot be used so continuously as meat without becoming monotonous; that is to say, a person will grow tired of fish much more quickly than of most meats. The similarity between the composition of fish and that of meat has much to do with regulating the price of these protein foods, which, as has already been learned, are the highest priced foods on the market.
6. PROTEIN IN FISH.--In fish, as well as in shell fish, a very large proportion of the food substances present is protein. This proportion varies with the quantity of water, bone, and refuse that the particular food contains, and with the physical structure of the food. In fresh fish, the percentage of this material varies from 6 to 17 per cent. The structure of fish is very similar to that of meat, as the flesh is composed of tiny hollow fibers containing extractives, in which are dissolved mineral salts and various other materials. The quantity of extractives found in these foods, however, is less than that found in meat. Fish extracts of any kind, such as clam juice, oyster juice, etc., are similar in their composition to any of the extractives of meat, differing only in the kind and proportions. In addition to the muscle fibers of fish, which are, of course, composed of protein, fish contains a small quantity of albumin, just as meat does. It is the protein material in fish, as well as in shell fish, that is responsible for its very rapid decomposition.
The application of heat has the same effect on the protein of fish as it has on that of meat, fowl, and other animal tissues. Consequently, the same principles of cookery apply to both the retention and the extraction of flavor.
7. FAT IN FISH.--The percentage of fat in fish varies from less than 1 per cent. in some cases to a trifle more than 14 per cent. in others, but this high percentage is rare, as the average fish probably does not exceed from 3 to 6 or 7 per cent. of fat. This variation affects the total food value proportionately. The varieties of fish that contain the most fat deteriorate most rapidly and withstand transportation the least well, so that when these are secured in large quantities they are usually canned or preserved in some manner. Fish containing a large amount of fat, such as salmon, turbot, eel, herring, halibut, mackerel, mullet, butterfish, and lake trout, have a more moist quality than those which are without fat, such as cod. Therefore, as it is difficult to cook fish that is lacking in fat and keep it from becoming dry, a fat fish makes a more palatable food than a lean fish. The fat of fish is very strongly flavored; consequently, any that cooks out of fish in its preparation is not suitable for use in the cooking of other foods.
8. CARBOHYDRATE IN FISH.--Like meat, fish does not contain carbohydrate in any appreciable quantity. In fact, the small amount that is found in the tissue, and that compares to the glycogen found in animal tissues, is not present in sufficient quantities to merit consideration.
9. MINERAL MATTER IN FISH.--In fish, mineral matter is quite as prevalent as in meat. Through a notion that fish contains large proportions of phosphorus, and because this mineral is also present in the brain, the idea that fish is a brain food has become widespread. It has been determined, however, that this belief has no foundation.
FOOD VALUE OF FISH
10. FACTORS DETERMINING FOOD VALUE.--The total food value of fish, as has been shown, is high or low, varying with the food substances it contains. Therefore, since, weight for weight, the food value of fat is much higher than that of protein, it follows that the fish containing the most fat has the highest food value. Fat and protein, as is well known, do not serve the same function in the body, but each has its purpose and is valuable and necessary in the diet. Some varieties of fish contain fat that is strong in flavor, and from these the fat should be removed before cooking, especially if the flavor is disagreeable. This procedure of course reduces the total food value of the fish, but it should be done if it increases the palatability.
11. RELATIVE NUTRITIVE VALUE OF FISH AND MEAT.--When fish and meat are compared, it will be observed that some kinds of fish have a higher food value than meat, particularly if the fish contains much fat and the meat is lean. When the average of each of these foods is compared, however, meat will be found to have a higher food value than fish. To show how fish compares with meat and fowl, the composition and food value of several varieties of each food are given in Table I, which is taken from a United States government bulletin.
TABLE I
COMPARISON OF COMPOSITION AND FOOD VALUE OF FISH AND MEAT
| Edible Portion | Composition | Total Food Value per Pound Calories | Food Value per Pound Due to Protein Calories | |
| Protein Per Cent. | Fat Per Cent. | |||
| Fish: | ||||
| Bass, black | 20.6 | 1.7 | 443 | 373 |
| Bluefish | 19.4 | 1.2 | 401 | 352 |
| Carp | 17.4 | 2.6 | 421 | 315 |
| Catfish | 14.4 | 20.6 | 1,102 | 262 |
| Halibut steak | 18.6 | 5.2 | 550 | 337 |
| Lake trout | 17.8 | 1.0 | 363 | 323 |
| Red snapper | 19.2 | 1.0 | 389 | 348 |
| Salmon (canned) | 21.8 | 12.1 | 888 | 396 |
| Whitefish | 22.9 | 6.5 | 680 | 415 |
| Meat: | ||||
| Beef, round, medium fat | 20.3 | 13.6 | 895 | 368 |
| Chicken, broilers | 21.5 | 2.5 | 492 | 390 |
| Fowl | 19.3 | 16.3 | 1,016 | 350 |
| Lamb, leg | 19.2 | 16.5 | 870 | 348 |
| Pork chops | 16.6 | 30.1 | 1,455 | 301 |
12. A study of this table will show that on the whole the percentage of protein in the various kinds of fish is as much as that in meat, while in a few instances, it is greater. This proves that so far as the quantity of protein is concerned, these two foods are equally valuable in their tissue-forming and tissue-building qualities. It will be seen also that the percentage of fat in fish varies greatly, some varieties containing more than meat, but most of them containing less. Furthermore, the total food value per pound, in calories, is for the most part greater in meat than in fish, whereas the food value per pound due to protein is equivalent in most cases, but higher in some of the fish than in the meat.
13. It must also be remembered that the drying or preserving of fish does not in any way decrease its food value. In fact, pound for pound, dried fish, both smoked and salt, contains more nutritive value than fresh fish, because the water, which decreases the food value of fresh fish, is driven off in drying. However, when prepared for eating, dried fish in all probability has more food value than fresh fish, because water or moisture of some sort must be supplied in its preparation.
14. The method of preparing dried or preserved fish, as well as fresh fish, has much to do with the food value obtained from it. Just as nutritive value is lost in the cooking of meat by certain methods, so it may be lost in the preparation of fish if the proper methods are not applied. To obtain as much food value from fish as possible, the various points that are involved in its cookery must be thoroughly understood. Certain facts concerning the buying of fish must also be kept in mind. For instance, in canned fish, almost all the bones, skin, and other inedible parts, except the tails, heads, and fins of very small fish, have been removed before packing, indicating that practically all the material purchased is edible. In the case of fresh fish, a large percentage of what is bought must be wasted in preparation and in eating, the percentage of waste varying from 5 to 45 per cent.
15. DIGESTIBILITY OF FISH.--The food value of any food is an important item when its usefulness as a food is taken into account, but of equal importance is the manner in which the body uses the food; that is, whether it digests the food with ease or with difficulty. Therefore, when the value of fish as a food is to be determined, its digestibility must receive definite consideration. As has already been explained, much depends on the cooking of the food in question. On the whole, fish is found to be more easily digested than meat, with the exception perhaps of a few kinds or certain cuts. That physicians recognize this characteristic is evidenced by the fact that fish is often used in the feeding of invalids or sick people when meat is not permitted.
16. The ease with which fish is digested is influenced largely by the quantity of fat it contains, for this fat, acting in identically the same way as the fat of meat, has the effect of slowing the digestion that is carried on in the stomach. It follows, then, that with possibly one or two exceptions the kinds of fish most easily digested are those which are lean.
17. In addition to the correct cooking of fish and the presence of fat, a factor that largely influences the digestibility of this food is the length of the fibers of the flesh. It will be remembered that the parts of an animal having long fibers are tougher and less easily digested than those having short fibers. This applies with equal force in the case of fish. Its truth is evident when it is known that cod, a lean fish, is digested with greater difficulty than some of the fat fish because of the length and toughness of its fibers. This, however, is comparative, and it must not be thought that fish on the whole is digested with difficulty.
18. Another factor that influences the digestibility of fish is the salting of it. Whether fish is salted dry or in brine, the salt hardens the fibers and tissues. While the salt acts as a preservative in causing this hardening, it, at the same time, makes the fish preserved in this manner a little more difficult to digest. This slight difference need scarcely be considered so far as the normal adult is concerned, but in case of children or persons whose digestion is not entirely normal its effect is likely to be felt.
TABLE II
NAMES, SEASONS, AND USES OF FRESH FISH
| NAME OF FISH | SEASON | METHOD OF COOKERY |
| Bass, black | All the | Fried, baked |
| Bass, sea | All the year | Baked, broiled, fried |
| Bass, striped | All the year | Baked, broiled, fried |
| Bass, lake | June 1 to January 1 | Baked, broiled, fried |
| Bluefish | May 1 to November 1 | Baked, broiled |
| Butterfish | October 1 to May 1 | Fried, sautéd |
| Carp | July 1 to November 1 | Baked, broiled, fried |
| Catfish | All the year | Fried, sautéd |
| Codfish | All the year | Boiled, fried, sautéd, baked, broiled |
| Eels | All the year | Fried, boiled, baked |
| Flounder | All the year | Sautéd, fried, baked |
| Haddock | All the year | Steamed, boiled, fried |
| Halibut | All the year | Boiled, fried, creamed |
| Herring | October 1 to May 1 | Sautéd, fried, broiled |
| Kingfish | May 1 to November 1 | Boiled, steamed, baked |
| Mackerel | April 1 to October 1 | Baked, broiled, boiled, fried |
| Perch, fresh water | September 1 to June 1 | Fried, broiled |
| Pike, or pickerel, fresh water | June 1 to January 1 | Fried, broiled, baked |
| Porgies, salt water | June 15 to October 15 | Fried, sautéd |
| Red snapper | October 1 to April 1 | Boiled, steamed |
| Salmon, Kennebec | June 1 to October 1 | Broiled, baked, boiled |
| Salmon, Oregon | October 1 to June 1 | Broiled, baked, boiled |
| Shad | January 1 to June 1 | Baked, broiled, fried |
| Shad roe | January 1 to June 1 | Broiled, fried |
| Sheepshead | June 1 to September 15 | Boiled, fried |
| Smelts | August 15 to April 15 | Fried, sautéd |
| Sole, English | November 1 to May 1 | Baked, broiled, fried |
| Sunfish | May 1 to December 1 | Fried, sautéd |
| Trout, fresh water | April 1 to September 1 | Baked, broiled, fried, boiled, sautéd |
| Weakfish, or sea trout | May 15 to October 15 | Baked, broiled |
| Whitebait | May 1 to April 1 | Fried, sautéd |
| Whitefish, fresh water | November 1 to March 1 | Baked, fried, sautéd, broiled |