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   Chapter 5 No.5

Public School Domestic Science By Adelaide Hoodless Characters: 13081

Updated: 2017-11-30 00:04


Foods Containing Protein, or Nitrogenous Matter.

Animal foods contain nutritive matter in a concentrated form, and being chemically similar to the composition of the body is doubtless the reason why they assimilate more readily than vegetable foods, although the latter are richer in mineral matter. The most valuable animal foods in common use are meat, eggs, milk, fish, gelatin and fats.

MEAT.

Meat is composed of muscular tissue, connective tissue or gristle, fatty tissue, blood-vessels, nerves, bone, etc. The value of meat as food is due chiefly to the nitrogenous compound it contains, the most valuable being the albuminoids: the gelatinoid of meat is easily changed into gelatin by the action of hot water. Gelatin when combined with the albuminoids and extractives has considerable nutritive value. Extractives are meat bases, or rather meat which has been dissolved by water, such as soup stock and beef tea. The object in cooking meat is to soften and loosen the tissue, which renders it more easily digested. Another object is to sterilize or kill any germs which may exist and to make it more palatable. The digestibility of meat is influenced by the age of the animal killed and the feeding. The following table is given as an average of the digestibility of animal foods:-

Table of Comparative Digestibility.

Commencing with the most digestible and ending with the least

digestible of meats and other animal foods. (Thompson.)

Oysters.

Soft cooked eggs.

Sweetbread.

Whitefish, etc.

Chicken, boiled or broiled.

Lean roast beef or beefsteak.

Eggs, scrambled, omelette.

Mutton.

Bacon.

Roast fowl, chicken, turkey, etc.

Tripe, brains, liver.

Roast lamb.

Chops, mutton or lamb.

Corn beef.

Veal.

Duck and other game.

Salmon, mackerel, herring.

Roast goose.

Lobster and crabs.

Pork.

Fish, smoked, dried, pickled.

Cooking affects the digestibility of meat, which is evident from the figures given in the following table (Church):-

Time of Digestion.

Hours.

Beef, raw 2

Beef, half boiled 21/2

Beef, well boiled 23/4 to 3

Beef, half roasted 23/4 to 3

Beef, well roasted 21/4 to 4

Mutton, raw 2

Mutton, boiled 3

Mutton, roasted 31/4

Veal, raw 21/2

Pork, raw 3

Pork, roasted 51/4

Fowl, boiled 4

Turkey, boiled 21/2

Venison, broiled 11/2

It may be well to add here that animal food is more digestible when cooked between 160° and 180° F. than at a higher temperature.

Cooking of Meat.

(For more general information, see Recipes.)

In boiling meat two principles must be considered, the softening of the fibre and preserving of the juices. If the meat alone is to be used it should be placed in sufficient boiling water to completely cover, and kept at boiling point (212° F.) for at least ten minutes, so as to harden the albumen and prevent the escape of the juices. The temperature should then be allowed to fall to simmering point (175° F.). If the water is kept boiling it will render the meat tough and dry. If the juice is to be extracted and the broth used, the meat should be placed in cold water; if bones are added they should be cut or broken into small pieces in order that the gelatin may be dissolved. If the water is heated gradually the soluble materials are more easily dissolved. The albumen will rise as a scum to the top, but should not be skimmed off, as it contains the most nutriment and will settle to the bottom as sediment.

STEWING.

If both meat and broth are to be used the process of cooking should be quite different. In stewing, the meat should be cut into small pieces, put into cold water in order that the juices, flavoring material and fibre may be dissolved. The temperature should be gradually raised to simmering point and remain at that heat for at least three or four hours, the vessel being kept closely covered. Cooked in this way the broth will be rich, and the meat tender and juicy. Any suitable flavoring may be added. This is a good method for cooking meat containing gristle.

ROASTING and BROILING.

When the meat alone is to be eaten, either roasting, broiling or frying in deep fat is a more economical method, as the juices are saved. The shrinkage in a roast of meat during cooking is chiefly due to a loss of water. A small roast will require a hotter fire than a larger one, in order to harden the exterior and prevent the juices from escaping. Meat is a poor conductor of heat, consequently a large roast exposed to this intense heat would become burned before the interior could be heated. The large roast should be exposed to intense heat for a few minutes, but the temperature should then be reduced, and long steady cooking allowed.

Broiling (see broiling in previous chapter, p. 19.)

Varieties of Meat.

BEEF TONGUE.

Beef tongue is a tender form of meat, but contains too much fat to agree well with people of delicate digestion.

VEAL.

Veal, when obtained from animals killed too young, is apt to be tough, pale and indigestible, but good veal is considered fairly nutritious. It contains more gelatin than beef, and in broth is considered valuable, especially for the sick.

MUTTON.

Mutton is considered to be more digestible than beef, that is well fed mutton from sheep at least three years old; but as it is more difficult to obtain tender mutton than beef, the latter is more generally preferred. Mutton broth is wholesome and valuable in sickness.

LAMB.

Lamb, when tender and of the right age, is quite as digestible as beef or mutton, but the flesh contains too large a proportion of fat.

Fig. 1.-Diagram of cuts of beef.

Fig. 2.-Diagram of cuts of veal.

Fig. 3.-Diagram of cuts of pork.

Fig. 4.-Diagram of cuts of mutton.

VENISON.

Venison is a tender meat with short fibres, which is very digestible when obtained from young deer, but is considered to be rather too stimulating. Its chemical composition is similar to lean beef.

PORK.

Pork is a tender-fibred meat, but is very indigestible owing to the high percentage of fat, which is considerably more than the nitrogenous material it contains. Pork ribs may have as much as 42 per cent. of fat.

HAM AND BACON.

Ham is more digestible when well boiled and eaten cold. Bacon is more easily digested than either ham or pork; when cut thin and cooked quickly-until transparent and crisp-it can often be eaten by dyspeptics, and forms an excellent food for consumptives.

FOWL.

Chicken is one of the most

digestible of meats, contains considerable phosphorus and is particularly valuable as food for invalids. Turkey is somewhat less digestible than chicken. Ducks and geese are difficult of digestion, unless quite young, on account of the fat they contain.

GAME.

Game, if well cooked, is fairly digestible.

SWEETBREAD.

Sweetbread, which is thymus gland of the calf, is a delicate and agreeable article of diet, particularly for invalids. Tripe, heart, liver and kidneys are other forms of animal viscera used as food-valuable chiefly as affording variety.

FISH.

The chief difference in fish is the coarseness of fibre and the quantity of fat present. Fish which are highly flavored and fat, while they may be nutritious, are much less easy of digestion than flounder, sole, whitefish, and the lighter varieties. The following fish contain the largest percentage of albuminoids:-Red snapper, whitefish, brook trout, salmon, bluefish, shad, eels, mackerel, halibut, haddock, lake trout, bass, cod and flounder. The old theory that fish constituted "brain food," on account of the phosphorus it contained, has proved to be entirely without foundation, as in reality many fish contain less of this element than meat. The tribes which live largely on fish are not noted for intellectuality. Fish having white meat when broiled or boiled-not fried-are excellent food for invalids or people of weak digestion. Fish should be well cooked.

OYSTERS.

Oysters are a nutritious food, and may be eaten either raw or cooked. Lobsters, crabs and shrimps are called "sea scavengers," and unless absolutely fresh are not a desirable food.

MILK.

Milk contains all the elements which are necessary to maintain life; and constitutes a complete diet for infants. It will sustain life in an adult for several months. Although milk furnishes a useful food, it is not essential to a diet required for active bodily exercise. It is seldom given to athletes while in active training. Adults who are able to eat any kind of food are kept in better health by abstaining from milk, except as used for cooking purposes. An occasional glass of hot milk taken as a stimulant for tired brain and nerves is sometimes beneficial. Milk is composed of water, salts, fat, milk sugar or lactose, albumen and casein. Average milk has from 8 to 10 per cent. of cream. Good milk should form a layer of cream about 2-1/2 in. thick as it stands in a quart bottle. Lactose (milk sugar) is an important ingredient in milk. It is less liable to ferment in the stomach than cane sugar. In the presence of fermenting nitrogenous material it is converted into lactic acid, making the milk sour. Casein is present in milk chiefly in its alkaline form, and in conjunction with calcium phosphate. Milk absorbs germs from the air and from unclean vessels very readily. Good, clean, uncontaminated milk ought to keep fresh, exposed in a clean room at a temperature of 68° F., for 48 hours without souring. If the milk is tainted in any way it will sour in a few hours. Boiled milk will keep fresh half as long again as fresh milk. Milk absorbs odors very quickly, therefore should never be left in a refrigerator with stale cheese, ham, vegetables, etc., unless in an air-tight jar. It should never be left exposed in a sick room or near waste pipes. Absolute cleanliness is necessary for the preservation of milk; vessels in which it is to be kept must be thoroughly scalded with boiling water, not merely washed out with warm water.

Methods of Preserving Milk.

STERILIZED MILK.

Milk to be thoroughly sterilized and germ free must be heated to the boiling point (212° F.). This may be done by putting the milk into perfectly clean bottles and placing in a rack, in a kettle of boiling water, remaining until it reaches the necessary degree of heat. The bottle should be closely covered immediately after with absorbent cotton or cotton batting in order to prevent other germs getting into the milk.

PASTEURIZED MILK.

The difference between pasteurizing and sterilizing is only in the degree of heat to which the milk is subjected. In pasteurizing, the milk is kept at a temperature of 170° F. from 10 to 20 minutes. This is considered a better method for treating milk which is to be given to young children, as it is more easily digested than sterilized milk. All milk should be sterilized or pasteurized in warm weather, especially for children.

CHEESE.

Cheese is one of the most nutritious of foods, and when meat is scarce makes an excellent substitute, as it contains more protein than meat. Cheese is the separated casein of milk, which includes some of the fats and salts.

EGGS.

Eggs contain all the ingredients necessary to support life. Out of an egg the entire structure of the bird-bones, nerves, muscles, viscera, and feathers-is developed. The inner portion of the shell is dissolved to furnish phosphate for the bones. The composition of a hen's egg is about as follows (Church):-

White-In

100 parts. Yolk-In

100 parts.

Water 84.8 Water 51.5

Albumen 12.0 Casein and albumen 15.0

Fat, sugar, extractives, etc. 2.0 Oil and fat 30.0

Mineral matter 1.2 Pigment extractives, etc. 2.1

Mineral matter 1.4

The albumen-or the "white"-of an egg is greatly altered by cooking. When heated beyond boiling point it becomes a very indigestible substance. Eggs cooked at a temperature of about 170° F., leaving the whites soft, are easily digested. A raw egg is ordinarily digested in 1-1/2 hour, while a baked egg requires from 2 to 3 hours. Eggs baked in puddings, or in any other manner, form one of the most insoluble varieties of albumen.

GELATIN.

Gelatin is obtained from bones, ligaments, and other connective tissues. In combinations with other foods it has considerable nutritive value. The place given to it by scientists is to save the albumen of the body; as it does not help to form tissue or repair waste it cannot replace albumen entirely. Gelatin will not sustain life, but when used in the form of soup stock, etc., is considered valuable as a stimulant.

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Legumes-Peas, Beans and Lentils.

These vegetables contain as much protein as meat; yet, this being inferior in quality to that contained in meat, they can scarcely be given a place in the same class; therefore we will give them an intermediate position in food value between meat and grains. From the standpoint of economy they occupy a high place in nutritive value, especially for outdoor workers. (See Recipes.)

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