88 



OUR FOOD SUPPLY 



OTHER INVESTIGATIONS WHICH YOU CAN 

 CARRY ON 



1. Make a survey of the stores in your community to 

 see whether foods are kept and sold under sanitary condi- 

 tions. Report your findings to the class. 



2. Investigate the life and achievements of Louis Pasteur. 



READINGS WHICH WILL HELP ANSWER THE 

 PROBLEM QUESTIONS 



Why do we cook foods? It is quite likely that primi- 

 tive man lived almost entirely on uncooked foods. To- 

 day we consume most of our foods only after they are 

 cooked. 



Foods are cooked for at least three reasons. First, 

 cooking improves the flavor or makes food taste bet- 

 ter, as we more commonly say. Most of us do not 

 enjoy raw meat and raw vegetables, but, by cooking 

 and seasoning, these same substances may be trans- 

 formed into appetizing dishes. Second, cooking makes 

 most foods more digestible. The action of heat on 

 foods softens the tough fibers of meats and breaks 

 the cell walls around the starch in starchy foods. If 

 you have performed the experiment of cooking a po- 

 tato, mentioned at the beginning of the topic, you will 

 recall how this takes place. This is an aid to diges- 

 tion because the digestive juices are able to act more 

 readily on the food nutrients. Third, cooking foods 

 kills any disease-producing organisms they may con- 

 tain. Bacteria, molds, worms in fact, all living things 

 that contaminate food and cause human diseases are 

 killed by the heat of boiling water. Therefore it is 

 safer to eat cooked foods. 



Not all foods react in the same way to the action 

 of heat. Some foods may be less palatable and more 

 difficult to digest when cooked the wrong way than if 



Before cooking After cooking 



FIG. 128. STARCH CELLS 



they had not been cooked at all. Cooking requires 

 careful study and practice if one wishes to become 

 proficient at it. 



There are five common methods of cooking, and by 

 each method it is the action of heat that does the cook- 

 ing. Each method is simply a different way of apply- 

 ing the heat to the foods. The five methods are boiling, 

 in which foods are cooked in boiling water or in water 

 just below the boiling point as in stewing; broiling, in 

 which foods are cooked directly over the source of heat ; 



steaming, in which the foods are cooked in the steam 

 from boiling water; frying, in which the foods are 

 cooked in hot fats ; baking and roasting, in which the 

 food is placed in a container in a heated oven or over 

 a fire. 



MOLD 



BACTERIA 



MUSHROOM 



YEAST 



FIG. 129. FUNGI 



Fruits and vegetables are frequently sprayed or 

 coated with poisonous substances while growing to 

 prevent the ravages of certain insect pests. Often 

 these poisons remain on the fruits or vegetables until 

 they have reached the consumer. It is therefore al- 

 ways wise to wash thoroughly all such foodstuffs be- 

 fore they are eaten, cooked, or placed in a refrigerator 

 for storage. In the case of fruits and some vegetables, 

 the outer peel or leaves are removed. It is, however, 

 best to wash these foods also. 



Why do foods spoil? We learned in a previous 

 topic that green plants with the aid of sunlight make 

 food out of inorganic matter. There exists, however, 

 a group of plants comprising more than one-fourtli 

 of all the plants in the world that do not have chloro- 

 phyll in them and therefore cannot manufacture food. 



