CREAMERY BUTTER ilAKING 95 



the best milk is received toward the middle or close of the 

 run, it should be carried into the creamery and separated 

 by itself so as to secure the skim-milk without contamina- 

 tion from other milk of inferior flavor. 



It must not be supposed that any milk may be made into 

 a first-class starter by thorough pasteurization and inocu- 

 lation with good cultures of bacteria. The best starters 

 are possible only with the best milk. 



WHOLE MILK STARTERS. 



Where whole milk is used for making starters the cream 

 should always be skimmed off before using the starter. 

 Indeed it is good practice to skim ofif the top of any 

 starter before using as the surface is liable to become 

 contaminated from exposure to the air. 



ACIDITY OF STARTERS. 



It has already been stated that a starter is at its best 

 immediately after it has thickened when it usually shows 

 about .7% acid. It must not be supposed, however, that 

 all starters are at their best when they show this amount 

 of acid, because diiiferent starters thicken with different 

 degrees of acidity. Nor must it be supposed that a starter 

 that tends to sour very quickly is better than one that 

 sours slowly. Marshall, of the Michigan Agricultural 

 College, has recently found that when certain alkali pro- 

 ducing bacteria are associated with the lactic acid organ- 

 isms the milk sours more quickly than when the alkali 

 bacteria are not present. These alkali producing bacteria, 

 while they hasten the souring, produce an undesirable 

 flavor. This probably explains why starter-s that have a 

 tendency to sour very rapidly are often inferior to those 



