CONDENSED BUTTERMILK 181 



If the buttermilk comes from sweet cream butter or from 

 neutralized cream churnings, it is usually not sufficiently sour 

 for ready handling and rapid evaporation. It therefore should 

 be allowed to ripen before it is used. For this purpose it is held 

 in wooden storage tanks for one or more days, where it auto- 

 matically develops acidity due to the lactic acid bacteria with 

 which it is usually teeming. For most satisfactory operation the 

 buttermilk should have an acidity of approximately .6 per cent. 

 In some cases it may be necessary to inoculate it with lactic 

 acid starter in order to insure the desired acid development. 



Heating the Buttermilk. From the ripening tanks the but- 

 termilk is drawn or pumped into the hot wells, where steam is 

 turned direct into it until the temperature is raised to the boiling 

 point. This method of heating also keeps it agitated and pre- 

 vents the copious settling of the curd. 



Condensing. From the hot wells the boiling-hot buttermilk 

 is drawn into the vacuum pan. The buttermilk is preferably 

 drawn frrm the bottom of the hot wells, so.as to continuously 

 remove a portion of the settling curd. The buttermilk will 

 drop some of its curd in the hot wells. The. operation of the vacu- 

 um pan for buttermilk is the same as for milk. For general 

 directions the reader is referred to Chapter V on "Condensing." 



The first pans used for condensing buttermilk were tin 

 coated on the inside and had tinned copper coils, so as to mini- 

 mize the action of the acid on the copper. The tin coating was 

 of very short duration, however, especially that on the coils, so 

 that it was found impractical and too costly to use tinned vac- 

 uum pans. The pans now in use are not tinned. 



In the condensing of a thick and sluggish liquid, such as 

 buttermilk, it is of the greatest importance that the coil arrange- 

 ment in the vacuum pan be such as to insure maximum circula- 

 tion of the milk, otherwise the buttermilk is incapable to absorb 

 the heat fast enough and to expose enough surface to evapora- 

 tion, to make possible rapid concentration, the buttermilk fails 

 to freely boil up, it sluggishly bubbles in the bottom of the pan, 

 evaporation is slow, the capacity of the pan is greatly reduced, 

 and the cost of manufacture is increased. For detailed descrip- 

 tion of the proper coil arrangement see Chapter V on "'Descrip- 

 tion of Vacuum Pan." 



