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THE CREAMERY PATRON'S HANDBOOK. 



changes in temperature, but is dependent upon the growth of certain species 

 of bacteria that get into the milk. Notwithstanding the popular notion, 

 thunder storms in and of themselves do not sour milk. If milk is free 

 from bacterial or other living organisms, thunder or electric discharges are 

 unable to affect its acidity. It is the conditions that usually accompany 

 the thunder storms, such as damp, heavy, muggy weather conditions that 

 favor rapid bacterial growth that are the real cause of the more rapid changes. 

 The lactic acid bacteria are so widely distributed that their presence in 

 milk is always assured, and the fermentative change that they cause may 

 be considered as normal. 



In general their presence is advantageous in milk intended for cheese 

 making, as the whole process of manufacture favors the development of 

 this class to the exclusion of other kinds. Their enormous development in 

 green cheese cannot be without significance, and undoubtedly the rapidity 

 and character of the ripening process is largely determined by the develop- 

 ment of this group. 



GASSY MILK. 



The most dreaded fermentations with which the cheesemaker has to 

 contend are those in which gaseous by-products are formed. In the great 



FIG. 7. A "gassy" cheese made from tainted milk. Note not only its porous texture but the 

 distorted shape of the cheese, 



majority of instances, the organisms causing these changes belong to the 

 sour milk class, but in addition to the lactic acid that they form, they also 

 give off other decomposition products, among which are gases such as car- 

 bon dioxide and hydrogen, and various volatile ill-smelling compounds. Fer- 

 mentations of this character are almost sure to produce undesirable taints 

 that pass over into the cheese, materially injuring its quality. 



The appearance of "gassy" milk is due entirely to the presence of gas 

 producing bacteria. All of the phenomena in cheese making associated 



