Nitrogenous Foods

As previously stated, in a mixed diet meat and eggs are the chief sources of nitrogenous foods. Next to these come the legumes.

Meat

Meat is almost all digested in the stomach by the gastric juice, which changes it into peptone. It is needless to say that it should be thoroughly masticated that there may be no delay in the prompt action of the gastric juice upon it. If any part passes into the intestine undigested, the process is continued by the trypsin of the pancreatic juice. The peptone is absorbed as peptone and after it passes through the inner coating of the intestines, it is changed back to protein and carried by the blood and lymph to all tissues of the body, where it is used for growth and repairs. As stated, any excess of protein above that needed for growth and repair, is oxidized in the blood, yielding energy and heat, and the waste is eliminated through the kidneys and the bile. The red blood corpuscles, which are nitrogenous, are broken down in the liver and discharged through the bile.

TABLE IV—ANIMAL FOODS

Food Materials		Water Per Cent	Protein Per Cent	Fat Per Cent	Carbohydrates Per Cent	Ash Per Cent	Fuel Value Per Pound Calories
Beef, Fresh		54.0	17.0	19.0	......	O.7	1,105
	Flank	54.0	17.0	19.0	......	0.7	1,105
	Porterhouse	52.4	19.1	17.9	......	0.8	1,100
	Sirloin steak	54.0	16.5	16.1	......	0.9	975
	Round	60.7	19.0	12.8	......	1.0	890
	Rump	45.0	13.8	20.2	......	0.7	1,090
	Corned beef	49.2	14.3	23.8	......	4.6	1,245
Veal:
	Leg cutlets	68.3	20.1	7.5	......	1.0	695
	Fore quarter	54.2	15.1	6.0	......	0.7	535
Mutton:
	Leg, hind	51.2	15.1	14.7	......	0.8	890
	Loin Chops	42.0	13.5	28.3	......	0.7	1,415
	Lamb	49.2	15.6	16.3	......	0.85	967
Ham:
	Loin chops	41.8	13.4	24.2	......	0.8	1,245
	Ham, smoked	34.8	14.2	33.4	......	4.2	1,635
Sausage:
	Frankfurter	57.2	19.6	18.6	1.1	3.4	1,155
	Fowls	47.1	13.7	12.3	......	O.7	765
Poultry:
	Goose	38.5	13.4	29.8	......	0.7	1,475
	Turkey	42.4	16.1	18.4	......	0.8	1,060
Animal Viscera:
	Liver (sheep)	61.2	23.1	9.0	5.0	......	......
	Sweetbreads	70.9	16.8	12.1	......	1.6	......
	Tongue, smoked and salted	35.7	24.3	31.6	......	8.5	......
Brain:		80.6	8.8	9.3	......	1.1	......
Fresh Fish
	Bass large-mouthed Black, dressed	41.9	10.3	0.5	......	0.6	215
	Cod steaks	72.4	16.9	0.5	......	1.0	335
	Shad roe	71.2	23.4	3.8	......	1.6	595
	Whitefish, dressed	46.1	10.2	1.3	......	0.7	245
Preserved Fish:
	Halibut, salted, smoked and dried	46.0	19.1	14.0	......	1.9	945
	Sardines, canned	53.6	24.0	12.1	......	5.3	955
	Salmon, canned	59.3	19.3	15.3	......	1.2	1,005
Mollusks:
	Oysters, solid	88.3	6.1	1.4	3.3	0.9	235
	Round clams removed from shell	80.8	10.6	1.1	5.1	2.3	340
	Mussels	42.7	4.4	0.5	2.1	1.0	140
Crustaceans:
	Lobster, in shell	31.1	5.5	0.7	......	0.6	130
	Crab, in shell	34.1	7.3	0.9	0.5	1.4	185
	Shrimp, canned	70.8	25.4	1.0	0.2	2.6	520
	Terrapin, turtle, etc.	17.4	4.2	0.7	......	0.2	105

In the composition of meat, of course there is more or less fat, varying from two to forty per cent, according to the animal and to the condition at the time of killing.

It is possible to combine the fat and the lean of meat so as to meet the requirements of the body without waste. About ninety-seven per cent of the meat consumed is assimilated by the system, while a large part of the vegetable matter consumed is excreted as refuse. The compounds contained in the animal foods are much like those of the body, therefore, they require comparatively little digestion to prepare them for assimilation—this work having been done by the animal—while the vegetable compounds require much change by the digestive system before they can be used in the body.

Fish and sea foods are, many of them, rich in protein, as seen by the above table. Note that sardines contain the largest proportion of protein and next to these, shad roe.

There is a prevalent idea that fish is brain food. In so far as fish is easily digested, it builds brain tissue, but no more so than beef, or any food containing a goodly proportion of protein, easily digested, absorbed, and assimilated.

Lobsters are difficult of digestion and they contain little nutrition, so they are not valuable as a food.

Oysters, raw, are easier to digest than when cooked. Oysters should not be eaten during the spawning season from May to September.

Roasted flesh seems to be more completely digested than boiled meat, but raw meat is more easily digested than cooked. Roasted chicken and veal are tender, easily masticated, and easily and rapidly digested in the stomach. This is one reason why the white meats are considered a good diet for the sick-room, especially in the case of stomach difficulty. Fat meats remain in the stomach a much longer time than lean meats; thus, gastric digestion of pork, which is largely fat, is especially difficult. Fried pork, in which the fat is heated to a very high degree, is very difficult of digestion. (See page [197]).

The chief objection to pork, however, is that hogs are scavengers and live upon all sorts of refuse. Another objection is that in preparing hogs for the market, the effort of the farmer is to force the feeding and get them as fat as possible. This excess of fat may result in degeneration of the meat tissue. The latter objection does not hold, however, for hogs carefully fatted for home consumption, or for hogs which run in the forests and live upon nuts, as do the beech fed hogs of the south.

The best meats are from young animals which have been kept fat and have not been subjected to any work to toughen the muscles.

Preserved and canned meats should be eaten with the utmost caution, not only because of the inferior meat used in the preparation of these foods, but also from the fact that they may become putrid after being canned.

The proportion of albuminoids, gelatinoids and extractives in meat vary with different meats and with different cuts of the same meat.

The albuminoids of meat include the meat tissue, or the muscle cells. These constitute by far the greater part of the meat.

The gelatinoids are the connective tissue forming the sheath of the muscle and of bundles of muscles, the skin, tendons, and the casein of bone. Gelatines are made from these and, if pure and prepared in a cleanly manner, they are wholesome.

Gelatin is distinguishable in rich meat soups, which jelly upon cooling.

While the gelatinoids are not muscle, they keep the muscles from being consumed when starches, sugars, and fats are lacking, and, in this sense, may be considered more in the nature of carbohydrates.

The extractives consist of a substance within the lean meat, known as creatin. This creatin is not a food; it is an appetizer, and gives to cooked meats, broths, etc., their pleasing flavor. In case of anaemia where it is necessary to build up red blood corpuscles, it is desirable to have the patient take the blood of beef, the thought of which is usually repellant, but it may be made very palatable if it is heated sufficiently to bring out the extractives, or flavor, and then seasoned.

Unless the beef extracts on the market contain the blood tissue in addition to the extractives, they are not particularly nourishing and are only valuable in soups, etc., as appetizers.

One reason why meat soups constitute the first course at dinner is because the extractives stimulate the appetite and start the flow of gastric juices. Bouillons contain no nourishment, because the proteins have been coagulated by the vigorous boiling, but they may be used as a basis for vegetables, rice, or barley to give them flavor.

The best method is to make one’s own soup from the connective tissues (gelatinoids) and meat tissue.

Eggs

Eggs consist chiefly of two nutrients,—protein, and fat (ten per cent), combined with water, phosphorous, and ash. Eggs are a wholesome source of protein and are, therefore, classed as nitrogenous foods.

The fat and the iron are in the yolk, which is about one-third fat. The yolk also contains phosphorous and some ash. The white is practically free from fat but contains sulphur, phosphorous and a very little ash. The white and the yolk contain almost equal quantities of protein.

The white of the egg is said to be pure albumen; the chief ash constituent is common salt. The total phosphorous in the white of the egg is equivalent to about two per cent phosphoric acid and the total phosphorous in the yolk is equivalent to one per cent.

The dark stain made by eggs on silver is due to the sulphur contained in them. The iron in the egg is valuable to assist in building red corpuscles.

The large part of the egg, as other proteins, is changed, mostly in the stomach, into peptone, absorbed as peptone and then changed back again into protein after absorption. That not digested in the stomach is changed in the intestine, as is the case with other proteins.

Eggs are, no doubt, excellent articles of food for nutrition and for tissue building. They contain more water than cheese, but are more concentrated than milk or oysters. They have practically the same relative value in the diet as meat, and make a very good substitute for meat. Egg yolk in abundance is often prescribed where it is necessary to supply a very nutritious and easily assimilated diet.

One of the best methods of preparing eggs, which is especially valuable for those having delicate stomachs or for those who need to build up red blood corpuscles with the iron in the yolk, is in egg lemonade or orangeade. Thoroughly beat the egg, add the juice of half a lemon or orange, sugar to taste, and fill the glass with water.

The citric acid in these fruits partly digests the egg, changing it into egg albumin,—the egg becomes limpid, no longer stringy. From this condition the gastric juice quickly changes it to peptone.

Grape juice, cream, and cocoa may be used in place of lemon or orange, in order to give variety where it is necessary to take many of them, but the grape juice acid does not partially digest the egg as the juice of the lemon does.

Eggnog is another means of taking raw eggs.

One method which any housewife can use to test the freshness of eggs is to drop them into a strong, salt brine made of two ounces of salt to a pint of water. A fresh egg will at once sink to the bottom. After the third day the surface of the shell will be even with the surface of the water and with increasing age they will rise still higher.

There is a prevalent opinion that if an egg is boiled hard it is difficult of digestion, but this depends entirely upon the mastication. If it is masticated so that it is a pulp before swallowed, a hard boiled egg is digested as readily as a soft boiled one. If it is not thoroughly masticated, then an egg should not be boiled longer than three to four minutes, or should be put into boiling water and allowed to remain in the water for six minutes without actively boiling. The latter method cooks the egg through more evenly. Another method of cooking the yolk evenly with the whites is to put the egg in cold water, let it come to a boil, and then again immerse in cold water. Or the egg may be put in cold water, let come almost to a boil, removed from the stove, and let stand ten to twelve minutes in the hot water. Any one of the last three methods cooks the white and the yolk evenly.