No. 6. DEPARTMENT OF AGU1C(JLTUKE. 585 



(1.) Natural Starters. — Among the materials used as natural start- 

 ers in butter-making are buttermilk and cream from previous op- 

 erations ot butter-makitig, and whole milk or skim-milk soured under 

 special conditions. While there are different ways of preparing 

 natural home-made starters, the following method may be suggested 

 as one that will give good results, if properly carried out: Milk is 

 taken from a cow in perfect health, not too far along in lactation, 

 and kept under proper conditions of cleanliness. The udder and 

 under parts of the cow's body are brushed and then wiped with 

 a damp cloth, after which the cow is milked into a carefully cleaned 

 vessel, the first few streams of milk from the udder being thrown 

 away. The milk thus drawn is at once covered, taken to the dairy 

 and run through the separator. This skim-milk, put into a care- 

 fully cleaned receptacle, is carefully covered, brought to a tempera- 

 ture of 90 degrees F., after which it is placed where it will keep at 

 a temperature of 65 degrees F. to 70 degrees F. In twenty to twenty-, 

 four hours, the skim-milk will be found properly ripened or just 

 moderately thickened. In using this prepr.red starter for ripening 

 cream, the upper portico to the deptii of one or two inches is re- 

 moved and thrown away, the rest is strair.ed through a fine strainer 

 or hair seive into the cream, which should be at 70 degrees F., in 

 the proportion of two pounds of starter for 100 pounds of cream. 

 The starter should be thoroughly stirred into the cream, the cream 

 vat covered and kept at a temperature of 65 degrees F. to 70 degrees 

 F. Usually twenty-four hours will develop the proper amount 

 of acid for churning. When the cream is properly ripened, it should 

 just form a soft curd, not a hard curd. In case of over-ripening, 

 when the curd becomes too hard, there is danger that some of this 

 coagulated casein will get into the butter and injure its quality and 

 appearance. Some of this prepared starter, described above, may 

 be used in preparing a starter for the day following, putting a little 

 into skim-milk that has been heated to 180 degrees F. for thirty 

 minutes and then cooled down io 70 degrees F., and the starter 

 may thus be propagated from day to day; but this method of propa- 

 gating must not be continued too long, as the starter gradually be- 

 comes inoculated with undesirable forms of bacteria and sooner or 

 later is unfit for use. These natural starters may be used in either 

 pasteurized or unpasteurized cream. 



(2.) Pure-Culture Starters are special preparations consisting of 

 certain specific selected organisms, known to be adapted to the 

 work of cream ripening. There are on the market several difi:erent 

 preparations for ripening cream, consisting of special cultures. 'Such 

 commercial artificial ferments give the best results, when used in 

 pasteurized cream. The chief advantage found by experience to 



