242 



Milk and Its Products 



Aeration. Passing the milk through an elevated 

 strainer in such a manner that it may fall in 

 finely divided drops or streams through the air be- 

 fore it reaches the can, is one of the best means 

 of bringing about this end. This is known as 

 aeration. It cannot be depended 

 upon to destroy or even check the 

 germs of fermentations which may be 

 present/ in the milk, beyond that 

 due to the reduction of temperature. 

 It is not desirable that milk in- 

 tended for cheese making should 

 be cooled much below the tempera- 

 ture of the air, and one of the best 

 preparations of milk intended for 

 I cheese making is to allow it to 

 remain where it will be freely ex- 

 posed to a pure and moderately cool 

 atmosphere. Under ordinary condi- 

 eievated strainer. tioiis, the milks of the evening and 

 the succeeding morning are manufactured together, 

 and the treatment indicated is naturally that of the 

 night's milk. It is highly desirable, however, that 

 the milk of the- morning should be cooled to the 

 temperature of the atmosphere before it is taken to 

 the factory, and under ordinary conditions the milk 

 of the night and morning should be taken to the 

 factory in separate cans. 



Ripening. The lactic acid fermentation is prob- 

 ably one of the most important factors in all the 

 steps of cheese making, and to know to what ex- 



Fig. 39. 



