176 NEUTRALIZATION OF SOUR CREAM 



Effect of Amount of Carbondioxide in Cream, on Accuracy 

 of Acid Reduction. When determining the acidity present in 

 cream before neutralization by titration with sodium hydrox- 

 ide, the results show not only the lactic acid and the casein 

 acid present, but also the carbondioxide that cream may contain. 

 But the carbondioxide escapes during pasteurization, being ex- 

 pelled by heat; it, therefore, does not claim the alkalinity of 

 the lime added, and allows this alkalinity to further reduce the 

 lactic acid and casein acid of the cream. 



The carbondioxide content of cream is very variable. It 

 is largely the result of fermentation. In fresh and only moder- 

 ately sour cream it is very slight, while in highly acid cream 

 and especially in yeasty cream, it may be relatively great. 

 Hence, the addition of the amount of lime calculated to reduce 

 the acidity to a given point when based on the original acid 

 test of the cream before neutralization will, in the case of high 

 acid and fermented cream, drop the acidity to a sligthly lower 

 point than that calculated. This irregularity is somewhat mini- 

 mized by the heating of the cream in the forewarmer, which 

 expels a portion of the carbondioxide present before the cream 

 is tested for its original acidity, and the higher the temperature 

 to which the cream is heated in the forewarmer, the more of 

 the carbondioxide is liberated. This fact, however, should not 

 be interpreted to mean that it is desirable to heat the sour 

 cream excessively before neutralization. Such a practice would 

 in part forfeit the benefits of neutralization, causing, especially 

 in the case of thin, sour cream,, the formation of an abnormal 

 curd, with excessive loss of fat and the danger of white specks 

 in the butter. The temperature of the cream before neutral- 

 ization, either in the forewarmer or in the pasteurizing vat, 

 should not be raised above 90 degrees F., if these defects are 

 to be avoided in a dependable manner by neutralization. 



Effect of Time and Temperature on Accuracy of Acid 

 Reduction. The neutralizing action of the lime is Comparatively 

 slow, it is not instantaneous. The acid test of the cream, made 

 immediately after neutralization, does not show the full neu- 

 tralizing power of the lime. The per cent acid found in the 

 cream at that time is higher than the calculated per cent acid 



