VEGETABLES WITH SALAD DRESSING (A)
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.
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.