PASTEURIZATION. 185 



jnuch by pasteurization. The flavor of the butter made from 

 such pasteurized cream is usually not improved very much. 

 However, the keeping quality of butter made from poor cream 

 pasteurized is usually better than if no pasteurization had been 

 employed. If the inferior quality of cream and milk can be 

 pasteurized, neutralized with an alkali, such as powdered chalk 

 or bicarbonate of soda, then inoculated with a desirable species 

 of bacteria and re-ripened, the quality of butter can be im- 

 proved several points. But experiments carried on at the 

 Iowa Experiment Station indicate that the improvement in the 

 quality of butter is not very permanent. Immediately after it 

 has been made there is a very distinct improvement in the 

 quality of the butter from such cream, sometimes as much as 

 five points. But for some reason butter from cream that has 

 been neutralized in such a way does not seem to keep well. 

 Some days after its manufacture it begins to lose decidedly in 

 flavor and to assume a very rank condition. For this reason 

 this method of treating poor cream has not been generally 

 advocated. The deterioration that takes place in such butter 

 after standing seems to be due to chemical changes rather 

 than to biological changes. The butter referred to was kept 

 in a refrigerator at a temperature of about 50 F. ; if the rancid 

 flavors were due to the growth of micro-organisms, they should 

 not reveal themselves in so short a time. 



(5) Pasteurization increases the keeping quality of butter. 

 This is one of the greatest advantages of employing pasteuriza- 

 tion in butter-making. The advantage of keeping butter from 

 the time of large supply and small prices to the time of small 

 supply and higher prices, makes pasteurization in butter-making 

 of vital importance in improving the keeping qualities of butter. 

 Butter made from good pasteurized cream and washed in pas- 

 teurized water will keep about twice as long as butter made 

 from the same kind of cream not pasteurized and washed in 

 unpasteurized water. 



(6) If milk is pasteurized previous to skimming, closer 

 skimming can be obtained than if the milk were heated to a 



