Butter Making 
ii 
Propagation of the Starter. 
Commercial starters are put up by the different manufacturers 
in two forms, one a powder and the other a liquid. Inasmuch as ex¬ 
treme care has been exercised in their preparation to keep them free 
from contamination, it is important that they shall not be opened 
until ready to be used. This suggestion is offered since a person with 
the average curiosity would be tempted to open the bottle and taste 
or smell the contents, and in so doing expose it to dust and air con¬ 
tamination. 
The first step in the propagation of the starter is the preparation 
of what is known as the “mother starter.” One quart milk bottles 
are very convenient vessels for this part of the work. Some suitable 
cover or stopper must be provided for the bottles; Bushnell and 
Wright (i) recommended a cotton batting plug, while Hastings (2) 
uses an ordinary glass tumbler inverted over the mouth of the bottle. It 
is also necessary to have some instrument for transferring portions of 
the mother starter to other bottles in order to perpetuate the culture. 
For this purpose, Bushnell and Wright recommend a cotton swab 
attached to a piece of heavy copper wire; Hastings prefers a silver 
plated teaspoon with a piece of well tinned wire soldered to the han¬ 
dle to give length. 
Having procured a number of one quart milk bottles, they should 
be boiled thoroughly in water for thirty minutes and then allowed to 
drain in a clean place. Next, several of the bottles are two-thirds to 
three-fourths filled with fresh, clean, whole or skimmed milk, prefer¬ 
ably the former, the spoon or cotton swab inserted, and the bottle finally 
stoppered with a firm cotton plug covered with a glass tumbler. The 
bottles and contents are now sterilized in flowing steam for thirty to 
forty minutes on three consecutive days in order to kill the bacteria 
present in the milk. This sterilizing may be accomplished in a spe¬ 
cially constructed steamer or in an ordinary wash boiler provided 
with a false bottom or shelf on which to set the bottles. Such a de¬ 
vice is described fully by Bushnell and Wright (1). A common kitchen 
steamer will serve fairly well, provided it is high enough to admit 
the bottles and still permit the lid to fit down tight. Some authori¬ 
ties believe that better results are obtained when the milk is sterilized 
on one day only instead of three, their reason being that the pro¬ 
longed heating injures the milk for starter purposes since the lactic 
acid germ thrives best in milk which is heated less. The only ad¬ 
vantage in heating the milk three days is that it is rendered absolutely 
sterile, while one day’s heating would not destroy the resistant spore 
forms of the bacteria which might be present, and which, if allowed 
to develop in the mother starter, would spoil it for that purpose. 
This would be true especially if several bottles of milk, were steril- 
( 1 ) Bushnell and Wright: Bui.' No. 24 6 , Mich. Exp. Sta. 
( 2 ) toe. cit. 
( 1 ) loc. cit. 
