34 Condensed Milk and Milk Powder 



is heated in the hot wells. Such milk therefore is safe, unless it 

 contains excessive acid, 'as shown by, the acid test. 



A curd with gas holes, or that which is torn to pieces in the 

 tubes, shows the presence of gas-producing germs. These come largely 

 from manure and other filth, Among these are Bacillus coli. com- 

 munis, the natural inhabitant of the colon of the animal, and butyric 

 acid organisms which are spore bearers. The latter especially may 

 give rise to serious milk defects, causing "swell heads." Patrons 

 sending such milk should be looked after at once. 



If the curd dissolves or no curd is formed and the milk 

 changes into a transparent liquid, it usually is contaminated by 

 germs from the dust of hay and bedding, or polluted water. To 

 this class of organisms belong Bacillus subtilis, Bacillus fluorescein 

 liquifaciens, Plectridium foetidium, Bacillus putrificus, etc. Some 

 of these are violent gas producers and most of them are spore bear- 

 ers. They are the cause Si some of the most disastrous milk de- 

 fects. Dairies from which such milk comes should be vigorously 

 inspected and all milk from them should be rejected, until the pa- 

 trons have learned how to furnish sanitary milk. 



Milk that remains unchanged for twenty-four hours when sub- 

 jected to the fermentation test, suggests that it contains some pre- 

 servative. It is possible/ however, for milk produced under ideally 

 sanitary conditions to remain normal and unchanged even at these 

 high temperatures for several days. Where milk comes to the fac- 

 tory in bulk as is the case in the condensery, samples showing' ab- 

 normal keeping quality should be regarded with suspicion, and the 

 respective dairies should receive immediate and thorough inspec- 

 tion. 



Tests for Buttereat and Specific Gravity.— In the fac- 

 tories where the milk is not paid for on the butter 

 fat basis, composite samples should be taken daily, to be tested for 

 fat and specific gravity, at regular intervals of from two to four 

 weeks, in order to detect possible adulterations by skimming or by the 

 addition of water. For specific directions for the Babcock test, the 

 use of the lactometer and tests for preservatives see Chapter 

 XXIX "Chemical Tests and Analyses of Milk and Milk Products" 

 and Chapter XXX "Detection of Adulterants and Preservatives 

 Etc." 



