156 NEUTRALIZATION OF SOUR CREAM 



on the surface after the slaked, but undissolved lime has drop- 

 ped to the bottom. The lime water contains lime hydrate in 

 solution only. From the standpoint of ease of handling, rap- 

 idity of action and accuracy of neutralization, this clear lime 

 water would be most suitable. But lime is only very slightly 

 soluble in water. It is soluble to the extent of about .137 per 

 cent in cold water and to the extent of .075 per cent in boiling 

 hot water. The clear lime water is so weak and its neutral- 

 izing power so slight that, in order to reduce the acidity in 

 cream from say .85 per cent to .25 per cent, it would require 

 lime water equal in volume to approximately twice the volume 

 of the cream to be neutralized. Clear lime water, therefore, is 

 obviously not a practical neutralizer to use. 



A stronger lime hydrate must be used and this consists of 

 milk of lime. Milk of lime is a watery emulsion of lime hydrate 

 which contains, in addition to lime in solution, particles of un- 

 dissolved lime. The milk of lime is somewhat more difficult 

 to handle and the control of its strength is less easy, because 

 the undissolved particles of lime settle out very readily and 

 quickly. It is difficult to maintain a homogeneous emulsion of 

 it and its neutralizing action is somewhat slow. By proper 

 preparation and intelligent handling, however, the above ob- 

 jections are largely overcome. 



In order to consistently reduce the acidity in cream to 

 the standard of .25 per cent acid, and to determine the correct 

 amount of lime emulsion to use, it is necessary to prepare and 

 use a neutralizing emulsion of definite, known strength, and 

 that can be manipulated accurately and conveniently and that 

 lends itself to ready and even distribution and uniform action 

 in the cream. 



The mix can be made up direct from: the quick lime or 

 calcium oxide, in which case time must be taken to properly 

 slake it. Or it can be made up from hydrated lime which re- 

 quires no additional slaking. A good quality of hydrated lime 

 gives fully as satisfactory action as unslaked lime, and it re- 

 quires much less work and trouble to prepare the mix. Slak- 

 ing lime is a mason's job which is rarely looked upon kindly 

 or done properly by the creamery operator. Improperly and 



