June, 1922 



SCIENTIFIC AGRICULTURE 



336 



TABLE IV. 



Oid'ium and Yeast Counts of Butter. 8 Ontario Creameries, 1920. 

 76 non-reaetors with the Storch Test. June, July and Aug. 

 ABC 



E 



NOTE: Numbers above are counts per c.c. of butter. 



First column — Oidium lactis mold. Second column — Yeasts. 



* Over 100,000 per c.c. 



This medium has been found to be a con- 

 siderable improvement on whey agar acid- 

 ified with tartaric acid, such as has been 

 used in many laboratories for similar work 

 heretofore and has given excellent satisfac- 

 tion during the three years we have now had 

 it in use. 



Of the raw cream butter 1-10 c.c, 1-100 

 c.c, and 1-1,000 c.c. portions have been 

 plated, and of the pasteurized cream butter 

 1 c.c. 1-10 c.c, and 1-100 c.c. portions. 

 Dilutions were made by measuring, with 

 warmed pipettes, 10 c.c. portions of butter 

 (melted at 110° F. and well mixed) into 

 90 c.c. sterile water blanks warmed up to 

 110° F. After thorough shaking 10 c.c. of 

 this dilution was pipetted into another 90 

 c.c blank, the mixture being shaken and the 

 process repeated as often as required. Plates 

 have been incubated at 25'^ C, Oidium counts 

 being made after three days and yeast and 

 Penicillium counts after iive days. 



Mold colonies found on cultures made from 

 pasteurized cream butter are usually Oidium 

 lactis only, other tj'pes of molds, Penicillium 



particularly, however, appear from time to 

 time. 



Counts made during 1919 showed that 

 large numbers of yeasts and molds (Oidium 

 and Penicillium) were present in butter made 

 from unpasteurized cream. This is what we 

 would naturally expect, as no steps have 

 been taken to destroy these organisms which 

 we know are present in large numbers in 

 gathered cream. Counts given in Table I 

 are typical of many others obtained of butter 

 made from unpasteurized cream. 



During 1920 our attention was .concen- 

 trated on pasteurized cream butter, no counts 

 of raw cream butter being knowingly made. 

 Ta-ble II shows the distribution of molds 

 (Oidium lactis) and yeasts, as found by us 

 during 1920, in 337 freshly made lots of 

 pasteurized cream butter, all non-reactors 

 with the Storch Test. 



The 93 Dominion contest lots came from 

 30 different creameries, scattered all over 

 Canada, two, three or four in each of the 

 nine different Provinces. The 244 Ontario 



