1. Soak lettuce in ice water for half an hour.
2. Soak lettuce in ice water over night.
3. Wash lettuce and put it in an air-tight can or jar on ice in an ice-box; allow it to remain an hour or longer.
4. Wash lettuce, wrap in a damp cloth, and place on ice in an ice-box; allow it to remain an hour or longer.
5. Wash lettuce, wrap it in a damp cloth, and hang in the wind.
6. Pour a little French dressing (see below) over a lettuce leaf, and let it stand awhile.
How would you recommend keeping lettuce? How freshen it quickly? When should it be dressed?
B. Cooking Greens.
Pick over and wash very carefully in several waters spinach or other greens.
1. Cook for ten minutes in a saucepan without the addition of more water than remains from the washing, tossing frequently to prevent burning. Chop. Continue simmering until tender.
2. Cook uncovered in a large amount of salted water until tender.
Compare the flavor and color obtained by the different methods of cooking.
Season part of the spinach with salt, pepper, and butter, and serve with slices of hard-cooked eggs.
Pack the rest into a mold to cool. Serve as salad with one of the following dressings.
Use one-third to one-half as much vinegar or lemon juice as oil, and a quarter of a teaspoon of salt for each tablespoon of oil. Add a little pepper or paprika. Beat with a spoon till well blended.
Beat half a teaspoon of powdered sugar into a tablespoon of thick, sour cream, and season with salt, pepper, and lemon juice or vinegar to taste.
Water is found in nearly all foods. Its specific uses in the body have already been mentioned in the discussion of water.
Mineral matter, too, has been discussed, so that all that need be said here is to point out the fact that it is found generally in all foods. The kinds, as well as the amounts, differ greatly, and it is a difficult matter to try to supply definite amounts of all the different kinds. In general, however, those foods which contain large amounts of mineral matter should be eaten in abundant quantity. Meat, fats, and sugar, show so little ash that if too much of them is eaten the diet may easily fail to furnish a sufficient supply of mineral substances. The value of fruits and vegetables on account of their salts has already been emphasized.
"The proteins get their name from a word which means "first" or "chief." They received this name because they are the only foodstuffs which contain nitrogen and so are essential for building and repairing body tissue, for this also contains nitrogen. Besides nitrogen, they contain oxygen, hydrogen, and carbon, as well as other elements, such as sulphur and phosphorus, in smaller quantities. Meats, eggs and milk provide us with large amounts of animal protein. Protein is also found in our vegetable foods, - most of the nuts, some of the grains, and a few vegetables containing appreciable amounts.
The carbohydrate group receives its name because all the compounds in this class are composed of carbon, and of hydrogen and oxygen which are usually in the same proportion as in water. Starch, cellulose, and sugar, as well as pectin and dextrine, are all members of this group.
The fats contain only the three elements which are found in the carbohydrates, but they are present in quite different proportions. Oils are merely fats which are liquid at ordinary temperatures instead of solid.
As has already been said, the last three classes of foods act as fuels in the body, supplying it with energy. The energy which is thus supplied is the sole source of the energy of the body. It is used not only for maintaining the temperature, but for all muscular movement as well. It is, then, a matter of great moment, not only that the body should be supplied with enough protein for building material, but that it should also be supplied with enough energy. At first thought it might seem as if proteins could be used entirely for both these purposes and fats and carbohydrates omitted from the diet, but there is every reason to believe that the results would be bad, for a number of causes, one of which is that this would furnish the body with a great excess of nitrogen.
It is easy to see that enough energy must be furnished, but what is "enough" and how is the amount to be determined? This can be done by measuring the energy needed by the body, and the amount of energy supplied by various foodstuffs.
While energy may be measured in a variety of ways, for example, as work, measured in foot-pounds, or as light, measured in candle power, the energy value of foods is measured as heat in calories. The unit of measurement, the calorie, is the amount of heat necessary to raise the temperature of a kilogram (about a quart) of water one degree Centigrade, or it may be expressed as about the amount of heat that would raise the temperature of a pound of water four degrees Fahrenheit.
To determine the energy value of a foodstuff all that is necessary is to burn a given amount of it in such a way that all the heat given off shall be taken up by water. Then, knowing the amount of water and the rise in temperature, the number of calories given off can be calculated. Such an apparatus is called a calorimeter, from the word meter, or measure, and calor, a Latin word meaning heat. A hollow metal cylinder, containing the material to be burned and a supply of oxygen, is immersed in an insulated tank containing a measured amount of water. Combustion is started by sending an electric spark through the foodstuff. The heat given off passes through the metal cylinder into the water. The rise in temperature is very accurately determined by means of thermometers, and corrections are made for any unavoidable escape of heat.