98 Dairy Bacteriology. 



98. Restoration of "body" of pasteurized cream. 



The action of heat causes the tiny groupings of fat glob- 

 ules in normal milk (fig. 15) to break up, and with this 

 change which occurs in the neighborhood of 150 F., the 

 consistency of the liquid is diminished, notwithstanding 

 the fact that the fat-content remains unchanged. Bab- 

 cock and the writer l devised the following ' ' cure J ' for 

 this apparent defect. If a strong solution of cane-sugar 

 is added to freshly slaked lime and the mixture allowed 

 to stand, a clear fluid can be decanted off. The addition 

 of this alkaline liquid, which they call " viscogen," to 

 pasteurized cream in proportions of about one part of 

 sugar-lime solution to 100-150 of cream, restores the con- 

 sistency of the cream, as it causes the fat globules to 

 cluster together in small groups. 



The relative viscosity of creams can be easily deter- 

 mined by the following method (fig. 17) : 



Take a perfectly clean piece of glass (plate or picture 

 glass is preferable, as it is less liable to be wavy) . Drop 

 on one edge two or three drops of cream at intervals of 

 an inch or so. Then incline piece of glass at such an 

 angle as to cause the cream to flow down surface of glass. 

 The cream having the heavier body or viscosity will move 

 more slowly. If several samples of each cream are taken, 

 then the aggregate lengths of the different cream paths 

 may be taken, thereby eliminating slight differences due 

 to condition of glass. 



99. Pasteurizing* details. While the pasteurizing 

 process is exceedingly simple, yet in order to secure the 

 best results, certain conditions must be rigidly observed 

 in the treatment before and after the heating process. It 

 is a mistaken idea that any milk is fit for pasteurizing. 



1 Babcock and Russell, Bull. 54, Wis. Expt. Stat., also 13th Kept. 

 Wis. Expt. Stat, p. 81, 1896. 



