HOME PROJECTS [Footnote 122: See Lesson IX.]
SUGGESTIONS FOR HOME WORK.—Plan a week's diet for a small sister, brother, or other child in whom you are interested. (Follow suggestions given in Lesson CLXII.) Calculate the total Calorific value and Calories derived from protein. Does your menu consist of foods which furnish the proper Calorific value and Calories derived from protein?
SUPPOSED AIMS: (1) If your menus do not conform to the requirements, to change them so as to meet the requirements of the young child.
(2) If possible, to arrange to have your menus prepared and fed to the child, assisting as much as possible in the preparation of the food and in the feeding of the child.
DIVISION SEVENTEEN
FOOD PRESERVATION
LESSON CLXVI
THE PRINCIPLES OF PRESERVING FOOD
WHY FOODS SPOIL.—Most foods spoil or change readily,—fruits decay, milk sours, butter becomes rancid, and meat putrefies. Knowledge concerning the spoiling of foods makes it possible for the housekeeper to preserve foods from one season to another; it gives her the assurance that her preserved fruit will "keep."
The decay of foods is due largely to the existence of minute vegetable organisms or microorganisms. These microorganisms are molds, yeasts, and bacteria. The molds (see Figure 88) are visible to the naked eye, the yeasts (see Figure 86) and bacteria (see Figure 89) are microscopic in size. These plants exist everywhere, and in everything (except those things in which the organisms have been destroyed and prevented from reentering),—in the air, in and on foods, and all over our bodies. Like all plants, these organisms require warmth, moisture, and food for their most rapid growth. Oxygen is necessary for the growth of some of these plants.