FOOD COMBINATIONS.—From a dietetic standpoint, it is well to combine foods of different compositions. If a food is lacking in one or more of the foodstuffs, it should be combined with a food that supplies the missing nutrient. Bread contains little fat, and butter contains no carbohydrates; hence these two foods make a desirable combination. Vegetable oils, butter, and other fats make desirable additions to vegetables. Macaroni contains little fat, while cheese is rich in this foodstuff. Moreover, macaroni contains a small quantity of incomplete protein, while cheese is rich in complete protein. Hence macaroni and cheese make a good combination. In selecting foods to be used together, careful attention should be given to their composition.

EMULSION OF OIL; SALAD DRESSING.—As has been stated (see Breaking Up of Fats), to emulsify fat it is necessary to separate it into tiny globules, and to coat each globule with some materials, so that the droplets will remain separate. Various materials serve to emulsify fats. During digestion, fat is emulsified by means of a soap (see Experiment 36). Egg is another material which emulsifies fats. This fact is made use of in making Mayonnaise Dressing from vegetable oil and eggs. If one understands that the oil must be divided into globules, and that each globule must be coated with egg, the preparation of salad dressing becomes interesting and successful. It is evident that the fat should be added to the egg slowly and should be beaten while being added. If the oil and other ingredients are cold, a thicker dressing results. Quick mayonnaise, however, is an exception to this rule.

[Illustration: FIGURE 62—THE COMPOSITION OF ROOTS AND SUCCULENT
VEGETABLES (Revised edition)]

Since emulsion of fat is one of the processes of digestion, it would seem that fat in emulsified form would be most readily digested. This is true of some emulsified fats,—the fat of milk is one of the most readily digested. But when an emulsified fat is mixed with protein as in Mayonnaise Dressing, the digestion of the mixture is slower than if either of the foodstuffs were alone. Hence to some persons, Mayonnaise Dressing proves distressing.

MAYONNAISE DRESSING

1 egg yolk 1 tablespoonful vinegar 1 tablespoonful lemon juice 1/4 teaspoonful mustard 3/4 teaspoonful salt 1/2 teaspoonful sugar Cayenne 1 cupful vegetable oil 2 tablespoonfuls boiling water

Put the egg yolk into a mixing bowl, add hot vinegar, and mix thoroughly. Then add the lemon juice and dry ingredients. Let the mixture stand until cool. Then beat it with a Dover egg beater and while beating add the oil in small quantities,—about 1/2 tablespoonful at a time. Continue beating and adding the oil. When the mixture begins to thicken, the oil can be added in greater quantities. After all the oil is added, add the boiling water. Beat until the latter is thoroughly blended.

It has been found that the oil may be added more rapidly if the egg is acidified before mixing it with the oil. [Footnote 66: This is due to the fact that the acid reacts with the albumin of the egg to form a kind of salt which hydrates and takes up water from the mixture. The more water that can be taken out of an emulsion in the form of hydrates, the more easily will an emulsion be formed.] The addition of boiling water to the mixture after the egg and oil have been blended, prevents the oil from separating from the other ingredients.

[Illustration: FIGURE 63—THE COMPOSITION OF BUTTER AND OTHER FAT-YIELDING
FOODS (Revised edition)]

If desired, the whole egg may be used in place of the egg yolks. In case this substitution is made, all the ingredients other than the egg should be doubled in quantity, since 1 whole egg will emulsify 2 cupfuls of oil.

The flavor of refined corn, cottonseed, or peanut oil is mild and pleasing. These oils have less flavor than olive oil but are as nutritious. Their use lessens the cost of Mayonnaise Dressing. After opening a bottle of vegetable oil, it should be kept in a cold place. If it is rancid, it should not be used in salad dressing.

If Mayonnaise Dressing is made successfully, it is thick and smooth. If the dressing is thin and curdled, the oil has been added too quickly, i.e. it has not been emulsified.

To remedy Mayonnaise that has curdled, beat the yolk of an egg slightly, then add the dressing to it gradually, beating constantly.

Mayonnaise Dressing may be varied by the addition of chili or celery sauce, chopped hard-cooked eggs, chopped parsley, pimentos, and green peppers.

QUICK MAYONNAISE DRESSING [Footnote 67: Adding the entire quantity of oil at one time and mixing it with hot paste may seem an unusual procedure for making an oil dressing. The fact that the method is successful may be explained as follows: Mixing the acid with the egg forms a salt which hydrates the mixture, and thus aids in making favorable conditions for emulsifying the oil as explained in the footnote of a previous page. The starch paste also takes up water from the mixture. This makes it possible to emulsify the oil easily, and also to make a stable emulsion.]

2 egg yolks or 1 whole egg 2 tablespoonfuls vinegar 2 tablespoonfuls lemon juice 1 1/4 teaspoonfuls salt 1 teaspoonful sugar 1/2 teaspoonful mustard Cayenne 1 cupful vegetable oil

Into a mixing bowl put the eggs and vinegar. Mix well. Add the other ingredients. (It is not necessary to stir them.)

Prepare a thick paste as follows:

In the top part of a double boiler put

1/3 cupful flour 1 cupful cold water 1 tablespoonful butter

Mix thoroughly. Then stir and cook over boiling water at least 10 minutes.
At once (while it is hot) turn this paste into the egg and oil mixture.
Beat all the ingredients with a Dover egg beater until a thick, uniform
dressing results.

(Adapted from a recipe by Mrs. Hill.)

SEASONABLE VEGETABLE SALADS

Use seasonable vegetables in salads. Cucumbers, tomatoes, celery, and cooked cauliflower may be used in the fall. Cooked beets, cabbage, carrots, and olives may be used in the winter, and head lettuce, radishes, and cooked asparagus in the spring. Vegetables should be chilled, cut into desirable shapes, and served on lettuce with salad dressing. Beets are greatly improved by cutting into pieces, after cooking, and soaking for one hour in vinegar to which salt has been added. They may also be soaked in French Dressing.

A combination of vegetables and fruits makes a pleasing salad. Cucumbers and pineapple, celery and apples, olives and cooked cranberries are successful salad mixtures. The use of cheese, nuts, and peanuts with vegetables and fruits adds to the flavor and food value of salads. Uncooked carrots, cabbage, and peanuts dressed with French Dressing make a tasty salad.

Canned vegetables, "left over" cold vegetables, meat, and fish have a better flavor in salads if they are mixed with French Dressing and allowed to stand in a cold place for one hour before serving. This process is called marinating. If several meats or vegetables are used in the same salad, they should be marinated separately. Just before serving, Cream Salad Dressing or Mayonnaise Dressing may be added to marinated salad materials.

A salad consisting of lettuce or other uncooked leafy vegetables should not be dressed until it is ready to be served. The acid in salad dressing wilts the leaves.

QUESTIONS

Explain why it is necessary to add the oil to the egg mixture in small quantities.

Explain why it is that a curdled dressing can be remedied by adding it gradually to an egg.

What is the price per quart of olive oil? Of peanut oil? Of cottonseed oil? Of corn oil?

Find the difference in cost between a Mayonnaise Dressing made with corn, cottonseed, or peanut oil and one made with olive oil.

From the standpoint of composition, explain why fresh vegetables and
Mayonnaise Dressing make a suitable combination (see Figures 62 and 63).

How much Mayonnaise Dressing is generally used for one serving? How many will the above recipe serve?

Make a list of combinations of materials which make tasty salads.