TABLE 29. PERCENTAGE COMPOSITION OF EDIBLE PART OF FISH. FRESH BASIS. (CLARK AND ALMY)

Shad (Male)

Shad (Female)

Apr. 2 35.32

Apr. 13 34.17

Shad (Female)

Shad (Female) spent

14.43 1.34 3.18 1.112 0.621 0.074 0.0160 13.93 1.40 3.00 1.147 0.685 0.063 0.0182 May 22 26.00 5.87 1.29 2.91 0.980 0.549 0.058 0.0191 June 19 23.38 2.95 1.53 2.98 0.975 0.549 0.182 0.0178

Clark and Almy (1918) made a series of analyses of fish obtained from Philadelphia fish dealers, giving particular attention to the forms of nitrogen present (see discussion of ammonia or

ammoniacal nitrogen in poultry above) and to the influence of season upon the fat content of the fish. Since protein is computed from nitrogen content by means of a factor which Clark and Almy did not consider sufficiently well established for fish protein, they did not include a statement of the protein content in their table of analyses (Table 29). The reader may easily compute the percentage of protein as ordinarily computed for foods, by multiplying the percentage of total nitrogen by 6.25.

Clark and Almy lay considerable emphasis on the variations of fat content of fish with season of the year as found in their analyses, which show a considerably increased fat content in the summer and autumn.

Dill (1921), on the other hand, has analyzed large numbers of Pacific coast fishes and finds that, with some exceptions, the mackerel and mackerel-like fishes have an increasing fat content through the summer and early fall; but that in general the variations in composition of fishes " are frequently erratic and cannot be ascribed to known factors."

Daughters (1918) has studied the Pacific coast eulachon, which in his analysis showed 13.18 per cent protein and 11.21 per cent of fat in the edible portion. He concludes that "in food value the eulachon is equal to the salmon. It contains a higher percentage of fat than the salmon and in flavor is considered superior." For methods of dressing, cooking, and preserving the eulachon he refers to United States Bureau of Fisheries, Economic Circular 33 (1917).

Preserved Fish

Many kinds of fish are preserved in large quantities by drying, salting, smoking, canning, or by combinations of these processes. As illustrative of these industries the preparation of salt codfish, canned salmon, and sardines in oil will be outlined.

Preparation of salt cod. tering at Gloucester, Mass.

This is a New England industry cen-
The annual product (including cusk,

haddock, hake, and pollock which are caught and handled with the cod) is estimated to represent a catch of about 225,000,000 pounds. In a bulletin of the Bureau of Chemistry, United States Department of Agriculture, Bitting describes the process as follows:

The cod are separated into three classes, snappers, medium and large, according to their size. All codfish less than 16 inches from the curve of the nape to the hollow of the tail are designated as snappers; those more than 16 but under 22 inches are called medium, and those above 22 inches are rated as large. The codfish generally run snappers 4 per cent, medium 41 per cent, and large 55 per cent. The cusk and hake are generally divided into two sizes, the snappers under 19 inches and the large above that. Each class is weighed and kept separate, being examined for any evidence of spoilage as they are pitched out.

The curing of salt fish depends upon drying, and this is accomplished in three ways — by the use of salt, by pressure, and by exposure to the air, either in the open air or in a drier. In this country all three agents are employed, as it is not possible to dry the fish in the air alone, as is done in certain parts of Norway.

Salt acts as a drier as well as a preservative, as it abstracts moisture wherever it comes in contact with the tissue, whether this be in the kench in the boat or in the butt at the factory. In the strictly full-pickle fish (that is, fresh fish placed in the butt) the maximum effect of drying by means of salt is accomplished. All the water abstracted in making pickle is so much drying. Kenching and air drying are necessary to complete the operation, though the amount of water abstracted by the latter operations is not so great as is generally supposed. In the "kench cure" there is a combination of salting and pressure.

A very large proportion of the fish is cured by a combination of these two processes, being salted and kenched on board the boat and the work completed in pickle at the factory. One of the advantages of the pickle cure is that the fish can be handled at all seasons and at such a rate as the trade may demand. For the slack-salted fish the salt is used as a preservative and the drying is accomplished by pressure and in the air. This can be done only when the weather is favorable.

The more fully the drying is done by salt or by pressure, the less time is required on the flakes. Those dried for domestic consumption are not nearly so dry as those packed for export trade. In the former class the moisture content is usually between 43 and 51 per cent, while in the latter it is between 28 and 35 per cent. . . .

The fish are dried on flakes and the drying yard is known as the flake yard. The flake consists of a lattice bed about 8 feet wide, 30 inches high, and as long as the requirements may demand. The lattice used on this bed is made of triangular strips 1 inch on the base, and these are placed about 3 inches apart. The fish therefore rest upon a sharp edge about every 4 inches. This is for the purpose of giving the maximum circulation of air about the fish. One double-deck flake yard was seen, the space between decks being 18 inches.

At regular intervals along the flakes, crosspieces are provided over which to stretch a canvas to protect the fish from sunburn during hot weather. Boxes or coops are also provided to cover the fish during rains and at night.

The fish are spread out carefully on the flakes with the face side up, and the drying is continued as long as may be necessary for the particular grade of fish. The full-pickle fish are dried for the shortest period, as they cannot be skinned readily if too dry, and, furthermore, the trade seems to desire fish which are moist and not too hard, and these retain practically 50 per cent of their water. If the sun is fairly warm and there is a good breeze, the drying can be accomplished in about ten hours as the minimum time, but this may be greatly increased with unfavorable weather conditions. Only one drying is usual for the full-cured fish.

The slack-salted fish are generally dried for two days, kenched for two or three days to "sweat" them, then placed on the flakes again for one day. Porto Rican or hard-dried fish are dried for three days, "sweated" for two days, and then again dried for two days. The object of the "sweating" is to bring the moisture out of the interior of the fish. The drying on the flakes removes the moisture from the surface and crystallizes the salt, but to get the moisture out of the center of the meat the fish must be piled in the kench, where the dry salt takes up some of the remaining moisture, so that the second drying on the flakes has a greater effect. The full-pickle fish lose about 9 per cent of their weight in drying on the flakes. When cured, they retain about 50 per cent of their moisture, the slack-salted retain 35 to 40 per cent, and the hard-dried from 25 to 30 per cent.

The fish are taken to the skinning department according to the orders to be filled. If the fish are to be put up as "absolutely boneless," then the fins are pulled out and the skin pulled off. The skin is started at the napes and pulled in toward the middle of the back and then pulled toward the tail. If the fish has been properly cured, the skin can be stripped off clean without tearing the flesh. If it has been sunburned, the skin will not hang together well. After the back has been skinned the fish is turned over and the dark lining membrane of the napes is stripped forward so that the whole fish is clean. The remaining portion of the backbone is cut out and the fish