142 CONDENSED BUTTERMILK 



Separation of Whey by Gravity. Much of the so-called 

 condensed buttermilk that reaches the market is not the result 

 of evaporation of a portion of the water contained in the butter- 

 milk, but is produced by permitting the curd to settle by gravity 

 and then drawing off and rejecting the whey. 



In this case the fluid buttermilk is pumped into a wooden 

 tank, either a horizontal vat or a vertical stave tank. The tank 

 usually contains several outlets with gates, located at different 

 heights, to facilitate the removal of the whey. The tank may 

 or may not be equipped with steam pipes for heating. The butter- 

 milk is heated to boiling point in these tanks either by blowing 

 live steam into it, or by running steam through the pipes installed 

 in the tank. This heat is maintained for several hours. This causes 

 the casein to contract and settle to the bottom in the form of 

 fine particles of curd, leaving on top a clear whey. This whey 

 is drawn off through the gates located above the stratum of 

 curd. The residue, consisting largely of casein, water and some 

 lactic acid and milk sugar, represents the condensed buttermilk. 

 The concentration, or more correctly speaking, the reduction in 

 volume thus effected, is at the ratio of about 4 to 5 parts of fluid 

 buttermilk to one part of condensed buttermilk. It is obvious that 

 in this form of concentration all of the valuable food elements of 

 the buttermilk are not reclaimed. Most of the milk sugar and 

 much of the lactic acid escape in the whey and are lost. However, 

 the equipment required for this process is very simple and in- 

 expensive and the process requires no special knowledge on the 

 part of the creamery personnel. 



Evaporation in Vacuo. This is accomplished in a similar 

 manner as is the case in the manufacture of sweetened condensed 

 milk. The buttermilk is condensed in the vacuum pan. Earlier 

 trials of this method did not prove entirely satisfactory, especial- 

 ly because of the tendency of the curd in the buttermilk to stick 

 to the coils and the sides of the pan. Another objection was the 

 relatively high initial cost of equipment the vacuum pan and 

 pump. 



In order to avoid the sticking of the curd, attempts have been 



made to neutralize the buttermilk before evaporation by the ad- 



' dition to it of such alkalies and alkaline earths as sodium carbon- 



