222 UNSWEETENED CONDENSED Miuc DEFECTS 



of the fat globules, the efficiency of the homogenizer to prevent 

 fat separation is due also to the physical change of the casein as 

 the result of homogenization. The casein becomes more viscous. 

 The chief objection to the use of the homogenizer is its 

 effect on the casein of the milk, when subjected to excessive pres- 

 sure. Beyond certain limits of pressure homogenization so 

 affects the casein, that the latter is more prone to curdle in the 

 sterilizer. However, experience has amply shown that the maxi- 

 mum pressure required to prevent fat separation in the finished 

 product, is not great enough to seriously affect the behavior of 

 the casein during sterilization. Hence, the proper regulation of 

 the pressure and the intelligent use of the homogenizer, furnish 

 a satisfactory and reliable means to prevent fat separation. Under 

 average conditions, the use of sufficient pressure to reduce the 

 fat globules to one-third of their original size, practically 

 destroys the power of the fat globules to rise to the surface. A 

 pressure of approximately one thousand pounds per square inch, 

 makes possible this reduction of the size of the fat globules. 1 



Fermented Evaporated Milk. 



General Description. Fermented evaporated milk is evap- 

 orated milk, which after sterilization, has undergone fermenta- 

 tion. The type of fermentations found in this product varies 

 with locality, season of year and factory conditions. The con- 

 tents of the cans may have soured with curd formation, or a 

 curd may have formed without acid development, or the fer- 

 mentation may be gaseous, in which case the cans bulge, and 

 these gaseous fermentations may be accompanied by acid forma- 

 tion or by putrefactive products. In all cases of fermented milk 

 the product is entirely worthless. These defects are usually, 

 though not always, detected during the period of incubation. 



Fermented evaporated milk is the result, either of incomplete 

 sterilization, or of leaky cans. The causes of fermented evapo- 

 rated milk differ with the specific type of fermentations produced ; 

 they will be discussed separately and as relating to the respective 

 types of fermentations. 



Acid Fermentation, Sour, Curdled, Evaporated Milk 



1 For details on the use of homogenizer see Chapter IX on "Homogenizing," 

 page 105. 



