YEASTS. 45 



bacteria, and the dirtier the barn, the cows, the pails, 

 or the clothes and hands of the milker, the more bac- 

 teria the milk contains. 



The baking of bread should kill both the bacteria 

 and yeasts, as well as molds, if any are there. But 

 it will not do this unless continued for a long time, 

 because the inside of the loaf will not be raised to a 

 temperature sufficiently high. The moisture in the in- 

 terior prevents a temperature much higher than 212 

 and it may remain far be- 

 low this. 



In the laboratory bread 

 has been made from the 

 yeast plants found alive in 

 the center of a slack-baked 

 loaf. The bread should re- 

 main in the oven until well 



Fig. 27. Bacteria Found in the 



done, then when removed "Eyes- of Potatoes. 



it should be cooled as rap- 

 idly as possible, that all growth of yeast or bacteria 

 may be stopped. 



The custom of some housewives of wrapping the 

 hot loaf in thick cloth that the steam may soften the 

 crust is entirely wrong from a bacteriological stand- 

 point. 



During the baking the alcohol and carbon dioxide 

 are both driven off. 



Coarse breads, those containing much bran espe- coarse 

 cially, need thorough baking, because on the outside of Meals 

 the grains are often certain bacteria, the spores of 

 which are very resistant to even high heat. 



