230 CREAM-RIPENING AND STARTERS 



it early enough to prevent the development of acidity from going 

 too far. Under the varying conditions that exist in the dif- 

 ferent creameries each creameryman will have to decide for 

 himself the temperatures that best suit his conditions. What 

 the authors have aimed to do is to state the underlying prin- 

 ciples of successful starter and cream-ripening, and what they 

 would urge most is the intelhgent application of these prin- 

 ciples. 



Preparation of Commercial Starters. — All of the starters 

 mentioned above have been tested and are known to produce 

 good results. The first step in the preparation of a mother- 

 starter fstarterline) is to prepare preferably a glass jar or bottle 

 by thorough!}' cleaning and sterilizing it. Glass jars are used in 

 preference to any other vessel, because if they are unclean in any 

 way, it will be apparent. Secondly, there are no seams and no 

 places on the inside which will corrode, and in that way retain 

 unnoticeable dirt; and in the third place, the nature of the coag- 

 ulation can be readily observed through the glass. IMason jars 

 and sampling bottles are suitable. The kind of bottle which 

 is used for marketing milk gives very good results. 



The second step consists in selecting suitable milk. The 

 milk must be in as pure and sweet a condition as possible. A 

 good starter can be produced from either whole or skim-milk. 

 At one time skim-milk was given a decided preference for use in 

 the making of starters. But the xiews of some of our leading 

 bacteriologists and practical creamerymen, experienced in the 

 preparation and use of starters, have changed upon this point 

 and they now express a decided preference for the use of whole 

 milk starters. The reasons for this preference may be briefly 

 stated: The whole milk is generally more easily selected; it 

 is the practice in some of our best creameries to have some 

 farmer supply nn'lk, jjroduced under special sanitar\- conditions 

 and cooled promptly to a low temperature, for starter purposes. 

 The trouble of separating and a possible extra source of contam- 

 ination are avoided. I'he presence of the fat in the milk serves 

 two useful purposes; first, the cream that rises seals the starter 

 over and prevents contamination, and second, the exclusion of 



