620 MISCELLANEOUS FARM SUBJECTS 



pressed yeast cake. Yeast plants are practically everywhere and are 

 of many varieties. Even when we are able to utilize me life processes 

 of the yeast plant, its good offices, as we have seen in bread-making, 

 are paid for with a certain amount of food material. Food that is to 

 be protected from yeasts must be kept well below 70 to 90 F. 



The appearance of mold on foods is familiar to every housewife ; 

 mildew on cloth is a less commonly recognized form of mold. The 

 spores (i. e., the minute reproductive bodies) of the different varie- 

 ties of mold are everywhere and need only warmth and moisture to 

 enable them to grow. Absolute cleanliness in the storage place is 

 essential. Fresh air, sunshine, and whitewash are important aids. 

 The undue use of water should be avoided, as moisture is one of the 

 chief requisites of growth. A cellar may be kept dry by placing in 

 it dishes of unslaked lime, which takes up the moisture. When the 

 lime crumbles apart, it has become "slaked," will take up no more 

 water, and must be renewed. The growth of most molds is retarded 

 by light, ventilation, and low temperature. From the standpoint 

 of household sanitation bacteria are by far the most important of the 

 three groups of micro-organisms under consideration. They are very 

 widely distributed and found in all food exposed to dust and air, 

 milk being a favorite. We can not get away from them without 

 going into the highest mountains or to the polar regions ; but we can 

 protect our food supply from their undue growth. It is of primary 

 importance that bacteria be prevented from getting their start. 

 Hence, only such foods should be bought as are in the freshest and 

 best possible condition. They should be consumed as soon as possible 

 after purchase or subjected to the following conditions: Utensils 

 that come in contact with them must be thoroughly scalded, or better, 

 boiled. The hands and clothing of the worker must be kept clean. 

 Of cooked foods, moist vegetables, cooked fruits, made dishes like 

 meat pies and similar dishes are particularly liable to spoil or sour. 

 The temperature at which food is kept should be reduced, usually as 

 near the freezing point as possible. 



Since the water content of food must be above 25 per cent before 

 bacterial life is possible in it, we may preserve food by drying it. 

 This method, often in combination with salting and smoking, is ap- 

 plied to fish, meat, vegetables, and fruit. By exposing food to 150- 

 160 F. of heat for half an hour, almost all varieties of bacteria would 

 be killed. The spores would in certain cases resist this degree of heat. 

 The pasteurization of milk offers an example of a food that is kept 

 from spoiling by this method. 



Most varieties of bacteria are killed in a few hours by direct sun- 

 shine, but it must be direct. We may often make use of substances 

 that inhibit bacterial growth, such as a very heavy sugar solution, in 

 preserving fruits. Vinegar, spices, salt, and wood smoke have a like 

 effect, and their use is familiar in pickled and spiced vegetables and 

 fruits and in salted and smoked meats. 



Ptomaine Poisoning. In some foods bacteria in the early stages 

 of their action leave no disagreeable or unhealthful effects, so far as 

 yet proved. The gamey. taste given meat by hanging comes in part 



