STARTERS 141 
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 contarnina- 
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 off 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 different 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 starters that have a 
tendency to sour very rapidly are often inferior to those 
