BUTTERMILK. 359 



as much as 2"0 per cent., percentages higter than this denoting 

 that the churning has been inefficiently carried out. 



Ash. — The following composition is given by Fleischmann to 

 the ash of buttermilk : — 



TABLE LXXXVIII. 



Potaah, KjO, 24-53 per cent. 



Soda, NajO, 11-54 



Lime, CaO 19-73 



Magnesia, MgO, 3-56 



Phosphoric aeid, P,Oj, . . , .29-89 



Chlorine, CI 13-27 



Iron oxide, ico., 0*47 



102-99 

 Less oxygen = chlorine, . . 2-99 



100-00 



Buttermilk has usually a slightly acid flavour ; it does not, 

 however, taste quite like sour skim milk, but has a distinctive 

 smell and flavour of its own ; it is not known to what this is 

 due. 



On microscopic examination it is seen that the fat left is not 

 entirely in globules ; there exist many small nuclei consisting of 

 two or more fat globules. 



Chemical Control of Churning Operations.— The fat in the 

 buttermilk from each chuining should be estimated. Usually 

 less than 1 per cent, of fat may be considered satisfactory, but 

 if sweet cream is churned it is difficult always to keep within 

 this limit. Any percentage of fat above 2 must be considered 

 unsatisfactory, and the cause should be enquired into. This 

 may be due to the use of cream which is too thick, mixtures of 

 cream of different consistency and age, too high a temperature, 

 or too rapid churning. 



The fat in the cream to be churned should also be estimated. 

 It has been found that cream containing from 2-5 to 30 per cent, 

 of fat gives the most satisfactory results. If the cream contains 

 more than 40 per cent, of fat, the buttermilk is very high in fat, 

 and a larger percentage loss is obtained. 



The weight of fat in the butter pliifi the weight of fat in the 

 buttermilk should come within 2 per cent, of the weight of fat 

 in the cream used. If a larger difference is found, a needless 

 loss of fat is taking place, and the cause of this should be ascer- 

 tained. 



Table CXLI. (Appendix) gives the weight in pounds of butter 

 wliich may be expected to be produced on churning cream varying 

 in percentage of fat from 15 to 50. 



