204 STATE BOARD OF AGRICULTURE 



A DISCUSSION OF FARM DAIRY METHODS. 



BY GORDON H. TRUE. 



Bulletin 167. — Farm Department, 



In a consideration of tlie diHerent methods of separating cream from tlie milk of 

 wliicli it is a part, it is well to keep in mind the composition of milk. We speak 

 of milk as being composed of water, butter fat and solids not fat. Cream consists 

 of butter fat mixed with more or less milk. Skim milk, if the separation has been 

 complete, consists of the water and the solids not fat of the milk. Butter fat is 

 lighter than milk and the solids not fat are heavier, and when milk is allowed to 

 stand there is a more or less complete separation of the lighter parts of the milk 

 from the heavier, the butter fat coming to the top in the form of cream, while 

 the heavier skim milk settles to the bottom. The butter fat exists in the milk in the 

 form of minute globules v.Trying in size from one thirty-thousandth to one ten- 

 thousandth of an inch in diameter. The smaller the fat globules the larger the 

 relative amount of surface when compared with the volume and the greater the 

 resistance offered by the milk in comparison with their buoyancy. In other words, 

 the larger the fat globules the more rapidly do they rise to the surface. 



Other things being equal, the heavier the liquid in which these fat globules float 

 the more rapidly and completely will the separation take place. In the case of 

 milk, ihowever, those conditiions which make the skim milk heavier make it at the 

 same time a thicker and more viscous fluid, so that Avith the increase in specific 

 gravity tending to aid the separation there seems to be an increased thickness of 

 the fluid tending to retard it. Thus it is that the composition of milk comes to have 

 a practical bearing upon the problems of creaming. 



CREAMING. 



f^haJloir /w!(s.— The m-T-thod of creaming milk most commonly practiced is prob- 

 ably that in whidh the fresh milk is set in shallow tin or earthen vessels and allowed 

 to stand at the temperature of the room until, by the action of gravity, the heavier 

 parts of the milk find their way to the bottom of the vessel and the lighter parts 

 come to the top in the form of cream. This method w;is practiced by our mothers 

 and by our grandmothers for generations, and we speak of it nowadays as the old 

 shallow pan method. 



While it is undoubtedly true that very good butter has been made, and is still 

 being made, from cream raised by this process, it has its disadvantages. On ac- 

 count of the relatively large amount of room required for setting the milk in 

 shalloAV pans, it is hard to provide a place where suitable conditions can be main- 

 tained without considerable expense. It is clear that the milk should be set in a 

 room where the atmosphere is always pure and the temperature is under control. 



It is argued in favor of the shallow-pan system that it is inexpensive. This, is in 

 a sense true, but if the same conditions of temperature and purity of atmosphere 

 necessary in the other methods Avere insisted upon where shallow pans are used 

 this argument could no longer be brought forward. 



Too often Ave And that a part of the kitchen, pautry or collar is used as a milk 

 room, and that the use of these rooms for the cooking of food or the storage of food 

 and of vegetables makes them unfit places for the keeping of milk. A clean, sweet, 



