142 MARKET DAIRYING 
that sour less rapidly. Usually, too, starters after they 
have been propagated for some time, become intensely 
acid producing, which is probably due to contamination 
with the peculiar alkali producing bacteria. 
RENEWAL OI STARTERS. 
Under average creamery conditions it is policy to renew 
the starter at least once a month by purchasing a new 
bottle of culture. It will be found that after the starter 
has been propagated for two or three weeks bad germs 
will begin to manifest themselves as a result of imperfect 
pasteurization, contamination from the air, or from over- 
ripening, so that its original good flavor may be seriously 
impaired at the end of one month’s use. It is only where 
the utmost precautions are taken in pasteurizing the milk 
and ripening the starter, that it is possible to propagate 
a starter for many weeks and still maintain a good flavor. 
VALUE OF CARRYING SEVERAL STARTERS. 
There is always some possibility of losing a starter by 
overripening or by accidental contamination which would 
deprive the butter maker of the use of a starter for several 
days. To insure against this, butter makers should practice 
carrying a few extra ones in quart cans. This has the 
additional advantage of offering some choice. The best 
is, of course, always selected for regular use. The milk 
for the small starters should be sterilized rather than 
pasteurized. 
This practice of carrying several starters is strongly 
recommended. 
