316 IOWA DEPARTMENT OF AGRICULTURE. 



tained by selecting a number of different samples of the best milk com- 

 ing into the creamery into sterilized glass jars. The samples are al- 

 lowed to sour naturally at about seventy degrees Fahrenheit and the 

 sample which coagulates into a smooth, uniform curd and has a pleasant 

 mild acid taste, is selected and used as a mother starter. When inocu- 

 lated into a large sample of selected pasteurized milk, cooled to and 

 kept at a temperature of about seventy degrees Fahrenheit, until it be- 

 gins to coagulate, it will usually produce a starter which is equal and 

 many times superior to a commercial starter. 



The discovery of using pure cultures of commercial starters for 

 cream ripening dates back to 1890 by Professor Storch. Copenhagen, 

 Denmark, who found that certain species of acid-producing germs were 

 chiefly responsible for the production of the desirable flavors in butter. 

 Doctor Weigmann. Kiel, Germany, later isolated a species of germ from 

 milk which produced alcohol and lactic acid as by-products, and which, 

 according to experimental evidence deducted by him. was claimed to be 

 largely responsible for the flavors in butter developed during ripening. 

 Doctor Conn, at Storr's Station, Connecticutt, claims that the germs which 

 act upon the nitrogenous matter of milk are associated with the produc- 

 tion of desirable butter flavors. 



Whether a commercial starter or a natural one is the most profit- 

 able for a creamery to use would depend upon conditions. In large 

 dairies the certainty of conditions for getting first-class milk for starter:^ 

 is in a measure removed from the butter-maker. In comparatively small 

 creameries there are usually a few patrons who can be depended iipor. 

 to deliver good milk, which can be purchased and used for starters. 



It has not yet been proven Ihat one particular specie of bacteria is 

 responsible for the production of flavors, but it is agreed upon by all 

 scientists that the flavoring substances are excretion or decomposition 

 products of bacterial growth, and that the lactic acid producing types. 

 are the most desirable ones to have present. 



In preparing starters for cream ripening the whole problem is then 

 centered upon excluding from the starter as many undesirable germs 

 as possible and foster the development of the desirable ones. 



This fact was recognized years ago by practical men. long before 

 the scientists recommended the use of pure cultures. In European dairy 

 countries, the use of the buttermilk borrowed from a neighboring fac- 

 tory, to add to the cream in order to overcome abnormal conditions, was 

 a common occurrence. In Holland, sour whey borrowed from some other 

 factory, was used in order to overcome gassy fermentation in cheese 

 making. While the reasons for doing this were not well understood, the 

 underlying principle was involved, namely that of overcoming undesir- 

 able fermentations by adding ferments of an antagonistic kind, and in 

 that way subdue and in a large measure supplant the action of those 

 undesirable ones already present. 



The surest way of accomplishing this and excluding undesirable fer- 

 mentations from the cream is to use a good natural or commercial starter. 

 A secretary of a large co-operative creamery in the State of Massachu- 

 setts one said: "Our quality of butter is falling short: we are not 



