Poisonous Principles in Eggs.—While fresh eggs for most people form a food product entirely devoid of danger, nutritious and easily digestible, eggs may easily become injurious and even poisonous. According to experiments made by Bouchard (Scientific American, August 11, 1896, page 95), even fresh eggs, unless the sanitary conditions in which the fowls live are well cared for, may become very poisonous. The fowl producing eggs, as a rule, is not a cleanly animal, and this is especially true of the duck. Thus injurious organic material rich in microbes may contaminate the egg and the microbes may penetrate the shell thus rendering the egg unsuitable for consumption. Eggs contaminated in this way have given evidence of toxic phenonema even in a fresh state, Experiments have shown too that the food material of eggs if directly injected into the blood of an animal produces toxic effects whereas if injected into the stomach no unfavorable effects are produced. Egg albumin, that is, the albumin of the white of the egg, when fed in considerable quantities to animals partially escapes digestion and thus becomes a source of irritation and even of poisoning. There are many people who are remarkably sensitive to the influence of eggs and those who possess this idiosyncrasy are injured even by eggs which are perfectly harmless to other people. A large number of species of injurious microbes which infect eggs have been identified. These even are found in fresh eggs in the unsanitary conditions above mentioned. Eggs kept for a long while in cold storage or decayed in any way are extremely injurious. Fortunately decayed eggs are self protecting since they can only be eaten by accident. If, however, decayed eggs be eaten in diluted form by mixing with other foods they may be eaten without their characteristic odor or taste being known and thus great injury arises. It is advised in all cases where eggs are to be kept for some time even in cold storage to varnish them with some substance impenetrable to air. For this purpose, as has already been mentioned, soluble glass, which is chemically a silicate of soda, has been found extremely effective. Any of the varnishes which make the shell of an egg air tight tends to restrain the activities of bacterial life since the bacteria cannot live without air. The officials who inspect food should direct special care to the storing of eggs in order that no damage may result from keeping them too long in cold storage or otherwise. It must not be understood that poisoning by eggs is of common occurrence. In fact it is very rare. The fact that the egg itself, which is such a common article of diet, may be unsanitary and improperly kept is a matter of great concern to the consumer. Parasites in Eggs.-The egg also when produced in unsanitary conditions may become infected with parasites. Many of these are apparently harmless, but some are injurious and even dangerous. The mere fact that parasites may exist in eggs is of itself a sufficient reason for the consumer to insist that the eggs he eats, like the milk he drinks, shall be free from all infections due solely to carelessness in production. PART III. FISH FOODS. man. FISH. Fish furnish a very important and useful part of the animal food of Both the fish growing in fresh water and in salt water are generally edible. Usually the smaller-sized fish are considered more palatable, but this is not universally the case. The large-sized fish are apt to be coarse, and have a less desirable flavor than those of smaller size. The size of the fish usually depends upon the magnitude of the body of water in which the species grow, the largest being in the lakes and oceans, the medium-size in rivers, and the smallest in brooks. Fish are known chiefly by their common names, and these names are different for the same species of fish in different parts of the country. For instance, the term trout covers a multitude of species, and, likewise, under the term sardine a large number of different species or varieties of fish are considered. There is also a large number of varieties known as salmon, perch, bass, etc. In the following table are given the common and the scientific names of the principal food fishes used in the United States (see Report of U. S. Commission of Fish and Fisheries, 1888, pages 679-868): Some of the scientific names in the above list have been modified by recent research, but it is advisable to present the above classification for purpose of reference. The variations from these names will be given in the part of the discussion relating to the food value of fish, in which the classification of Jordan and Evermann is followed. Edible Portion of Fish.-As in the case of other animals large parts of fish as taken from the water are inedible. In the preparation of fish the head is usually removed, especially if the fish be of any size, and the entrails rejected. If the fish be scaly, the scales are also removed. The latter vary very greatly in different specimens according to species, size, etc. Usually the edible portion of the fish is larger in quantity than the inedible, though this is not by any means universally the case. Taking fish of all kinds together it may be said that from 55 to 60 percent of the total weight is edible. This, of course, excludes the bones as well as the other portions already referred to. Principal Constituents of the Flesh of Fish.-In the flesh of cattle, swine, and other edible animals already mentioned it is seen that the protein is the principal part of the edible portion. In many kinds of meat, however, the fat is the principal portion, as in bacon. In the flesh of fish the albuminoids occupy a more prominent part than in the flesh of domesticated animals. or game. In other words the proportion of fat, which is one of the principal ingredients of the flesh of other animals, is less than in the other kinds of flesh. The protein in the water-free substance often constitutes over 90 percent of the total matter, and rarely falls below 80 percent. The next most important constituent of the dry flesh of fish naturally is the fat. The average content of fat in the dry flesh of fish is under 10,-it rarely goes above 20 and sometimes falls as low as 2 or 3 percent. The mineral content of the dry flesh of fish is quite constant. It rarely falls below 4 or goes above 8 percent; 5 percent may be regarded as a fair average content of mineral matter. The mineral matter consists chiefly of phosphate of potash and lime, together with some common salt. In the analyses made by Atwater, adopted in the following pages, he grouped together the fish analyzed in proportion to the quantity of the edible portion or flesh which they contained. Groupings were also made on account of the dry substance in the flesh and in proportion to the water and fat which they contained. These tables are of value showing in a general way the relative food importance of the different specimens of fish. This classification is given in the following table: |