NATURE OF FERMENTED DRINKS 



lactic, which sours milk. The ammonia smell about stables 

 is caused by another form of fermentation due to the break- 

 ing down of compounds of nitrogen into ammonia. 



When the word " fermentation " is used alone, alcoholic 

 fermentation is usually meant. 



126. Alcoholic Fermentation. The fermentation of sweet 

 fruit, plant, or other vegetable juices, composed largely of 

 water containing sugar and flavoring matters, is based upon 

 the growth of a class of microscopic plants commonly known 

 as yeasts. This ceaseless action of minute forms of plant 

 life is closely al- 

 lied to that of 

 bacteria. 



There are many 

 varieties of the 

 yeast plant which 

 grow on the sur- 

 faces and stems 

 of fruit as it is 

 ripening. While 

 the fruit remains 

 whole these germs 

 have no power to 

 invade the juice, 



FIG. 58. Showing One of the More Common 

 Molds found on Fruit and Bread. 



The tiny stalks grow vertically into the air. The end of 

 and even When each thread swells into a small round knob, from the 



inside of which hundreds of minute bodies, called spores, 

 burst. At a is seen a large knob filled with spores. 



the skins are 

 broken the condi- 

 tions are less favorable for their work than for that of the 

 molds, which are the cause of the rotting of fruit. 



But when fruit is crushed and its juice pressed out, these 

 yeast germs are carried into it and cause a breaking up of 

 the sugar and a rearrangement of its elements. 



