The flesh of the crab is, therefore, essentially a nitrogenous food, containing only a small quantity of fat. A considerable portion of the ash is common salt.
Crawfish.—The crawfish may be regarded as a fresh-water lobster. It is found practically over the whole of the United States in the fresh waters but is not used to any extent for food purposes, except on the Pacific coast. It contains even a less proportion of edible matter than the lobster. The refuse, shell, etc., form about five-sixths of its weight. In the edible portion the water constitutes 81.22 percent, while the solid matters are only 18.78 percent.
Composition of the Water-free Substance of the Crayfish.—
Protein, 85.19 percent
Fat, 2.45 "
Ash, 6.98 "
Canned Lobster, Clams, and Crabs.—As in the case of oysters, there is a large industry in the United States engaged in the canning of the flesh of lobsters, clams, and crabs. The same precautions should be observed in the eating of these canned products as those mentioned in the case of salmon. Numerous instances of illness and sometimes of death have been recorded as the result of eating these canned products which have been imperfectly sterilized. When the flesh is canned immediately after the capture of the animal, before any incipient decomposition has taken place and when the sterilization is perfect, the canned product can be eaten without fear. Where the health of the people is so seriously involved, the factories where these products are prepared should be carefully inspected either by the municipal, state, or federal authorities. All material used in canning which is not perfectly fresh from the water is to be rejected and the processes employed in the preparation and sterilization must be those which will effectively secure a complete immunity from subsequent fermentation and the development of ptomain products.
Composition of Canned Lobster (Dry Substance).—
Protein, 81.46 percent
Fat, 4.64 "
Ash, 11.23 "
As seen from the above the composition of the dry substance in canned lobster, except content of water, is not perceptibly different from that of the fresh sample.
Composition of the Dry Substance of Canned Crabs.—
Protein, 79.10 percent
Fat, 7.55 "
Ash, 9.68 "
Shrimp (Crangon vulgaris).—The shrimp is a highly valued article of
