WHY DO FOODS SPOIL? 333 



we are usually more (20) About (21) of the Calories 



in one's diet should come from (22) or a ratio of 1:3:6 should 



be maintained between our (23) , (24) , and (25) 



STORY TEST 



BOB MAY BE A BETTER ENGINEER THAN DOCTOR 

 Read carefully and critically. List all the errors and suggest corrections. 



Just as it takes fuel to run a gasoline engine so it takes fuel to 

 run the human engine. The energy value of foods is measured 

 in Calories. A food Calorie is the amount of heat that will warm 

 one pound of water 1 F. Children of junior high school age 

 require less food than their parents because of their smaller size. 

 It is the oxidation of food that gives us heat to keep the body 

 temperature up to normal, 89.6 F. 



Last winter I had the grip, and developed a temperature of 

 104 F., so the nurse said, but I think she was wrong because I 

 was eating less food than when I was well. It is a good plan to 

 check your weight by standard weight tables to see whether you 

 are of proper weight for the best health. If you are too heavy, 

 stop eating protein because they are building foods. This will 

 give you less variety, but the only reason for a varied diet is because 

 one is likely to tire of a food unless he has a change often. 



PROBLEM IV. WHY DO FOODS SPOIL? 



What Causes Food to Spoil. It is a matter of common 

 knowledge that foods become unfit to eat if they remain 

 for any length of time exposed to air in a warm place. 

 They smell badly and probably taste worse. Sometimes 

 fuzzy growths which we call mold appear on them. Fruit 

 juices usually taste as if they had alcohol in them. Many 

 kinds of tiny plants cause these changes. 



Demonstration 2. To Show Action of Bacteria, Yeasts, and Molds. 



Make a solution of molasses and water, using about one part 

 of molasses to five parts of water. Put the solutions in two cups : 

 one exposed to the air in a warm place, the other kept as near 

 the ice as possible in the icebox. Observe the appearance of the 

 contents of the two cups from day to day. Is there any difference 

 in the odor? Is there any difference in taste? How do you 

 account for these changes? 



