214 EFFECT OP PASTEURIZATION 



The presence of enzymes in butter capable of splitting 

 butter fat and of attacking the curd is most probable, especially 

 in the case of butter made from an inferior quality of cream that 

 is contaminated with diverse species of bacteria and that is 

 several days old. It is reasonable to assume, therefore, that the 

 presence of these enzymes in butter, plays an important role in 

 the deterioration of butter with age. 



Since vat pasteurization is incapable of destroying the 

 activity of these enzymes, this process fails to preserve the 

 butter from the point of view of enzyme action. The flash 

 process at 180 degrees F., on the other hand, is destructive to 

 the activity of these enzymes and therefore assists in preserv- 

 ing the butter. This assumption is supported by experimental 

 results conducted at the Purdue Experiment Station, 1 which 

 show that there is a greater increase in the acid value, soluble 

 proteids and amino acids in storage butter made from cream 

 pasteurized by vat pasteurization at 145 degrees F. than by flash 

 pasteurization at 180 degrees F. 



Effect on Score of Butter. The same experiments also 

 demonstrated that, while the fresh butter made from cream 

 pasteurized by the flash process at 180 degrees F. scored no 

 higher than, and in the case of sour, unneutralized cream not as 

 high as, butter made from cream pasteurized with the vat process, 

 the scores of the same butter when 30, 60 and 90 days old 

 showed less deterioration in the case of the flash process than 

 the vat process of pasteurization. In the case of sour cream 

 that was not neutralized, however, the fresh butter of the 

 flash process had a very disagreeable, oily flavor, while that of 

 the vat process was free from oiliness. For further details 

 on the causes of oily flavor, see Chapter XVII on Butter Defects. 



The condition and quality of the cream at the time of 

 pasteurization are important factors in the determination of the 

 benefits of pasteurization, to the quality of the resulting butter. 

 The better the flavor and the lower the acidity of the cream 

 before pasteurization, the better will be the flavor of the but- 

 ter when fresh and after storage. However, experimental results 

 have amply demonstrated, that the butter from both, good and 



1 Hunziker, Mills and Spitzer, Pasteurization of Cream for Butter-making, 

 Purdue Bulletin No. 203, 1917. 



