NEUTRALIZATION OP SOUR CREAM 



171 



Table 33. Showing Relative Action of Sodium Hydrate, Lime 

 Water and Milk of Lime on Acidity in Serum of Cream. 



The figures in Table 33 show that when neutralization is 

 not carried to the neutral point, adding neutralizer sufficient only 

 to reduce the acidity to .25% acid, the lime water (lime in so- 

 lution) shows somewhat greater preference for the casein' than 

 for the serum and that this preference for the casein is greatly 

 augmented in the case of milk of lime. Both the lime water and 

 the milk of lime showed greater preference for the casein than did 

 the sodium hydroxide, hence the lime neutralizers had less alka- 

 linity left to act on the lactic acid in the serum, and reduced the 

 acidity in the serum to a lesser extent than did the sodium neu- 

 tralizer. It should be clearly understood here that this difference 

 of distribution of the neutralizing action between sodium hydrate 

 and calcium hydrate occurs only when the neutralization is not 

 carried to the neutral point. Tables 31 and 32 show that when 

 neutralization is carried to the neutral point, the sodium hydrate 

 fully neutralizes both the lactic acid in the serum and the acid 

 in the casein. This fact furnishes reliable proof that the acid test 

 with sodium hydroxide shows the total acidity in cream,. Its 

 results are, therefore, correct, and they demonstrate that the 

 incomplete acid reduction of the lime is not due to any short- 

 comings of the acid test of the cream, but must be due to the 

 great affinity of the lime for the casein which causes the me- 

 chanical combination of particles of undissolved lime with 

 particles of solid casein, thereby mechanically tying up a portion 



