3 i6 



MICROBIOLOGY OF MILK AND MILK PRODUCTS. 



figures where the milk was passed through a strainer composed of three 

 thicknesses of fine cheese cloth supported by wire gauze. 



Effect of Straining Upon Bacterial Content of Milk. 



The effect of straining upon the keeping quality is shown in the fol- 

 lowing experiments where the milk was strained through the same form 

 of strainer mentioned above and the samples kept at constant temperature 

 of 21 until coagulation. 



Not strained 

 Hours to coagulation 



Strained 

 Hours to coagulation 



Experiment No. i. 

 Experiment No. 2. 

 Experiment No. 3. 

 Experiment No. 4. 

 Experiment No. 5. 



It will be seen that in no case was the keeping quality of these samples 

 increased by the straining process while in some cases it was materially 

 injured. 



Cotton filters are more efficient than cheese cloth and in some cases the 

 keeping quality of the milk may be improved by this process. 



AERATION. This is the process of exposing the milk to the atmosphere 

 by allowing it to run over the surface of the aerator in a very fine film. 



