NEUTRALIZATION OP SOUR CREAM 153 



acts more slowly on the acid, distributing the evolution of car- 

 bondioxide gas over a longer period of time and lessening the 

 tendency of the cream to violently foam. 



Of the hydrates, lime appears to be the only really suitable 

 alkali to use. It is mild in its action, does not injure the flavor 

 of the butter when used intelligently, does not appreciably at- 

 tack the metal of the vats and other equipment, tends to form 

 with that portion of the casein with which it reacts, a precipi- 

 tate of relatively great stability and resistance against bacterial 

 action, and it combines with the curd first, rendering that por- 

 tion of the curd which enters into the composition of the butter 

 less acid thereby minimizing the acidity of the butter and 

 its deteriorating power. 



Sodium hydrate, the cheapest form of which, for neutral- 

 izing purposes, is soda lye, has strong caustic properties. It 

 and the sodium lactate w^hich it forms in the sour cream, readily 

 attack and dissolve metals such as copper and even tin* causing 

 the vat linings and coils and the pasteurizers to turn black and 

 the cream and butter to contain undue quantities of metallic 

 salts which are detrimental to its flavor and keeping quality. 

 Sodium, unlike lime, reacts with the lactic acid of the 

 cream first, and, inasmuch as in the neutralization of cream, 

 acid reduction is not carried to the neutral point, there 

 is but slight action on the casein, leaving the curd in butter 

 made from sodium-neutralized cream, in more acid condition 

 than is the case with butter from lime-neutralized cream. Again, 

 while in lime-neutralized cream the undissolved casein appears 

 in relatively large aggregates of marked firmness and apparent 

 insolubility, in sodium-neutralized cream the insoluble portion 

 of the casein is soft, it suggests greater solubility and less re- 

 sistence to bacterial action. 



The flavor of the butter made from cream neutralized with 

 soda lye, sodium carbonate, or sodium bicarbonate is prone to 

 have a soapy character. This is especially true of cream of 

 high original acidity and cream in which the acid is reduced 

 very close to the neutral point. With lime hydrate, properly 

 prepared and intelligently used and using a sufficient quantity 

 only to reduce the acidity to .25 per cent or thereabout, no ob- 

 jectionable flavor effects occur. 



