SCIENTIFIC AGRICULTURE 



June, 1922 



lots came from 40 different Ontario cream- 

 eries. 



Table III shows the distribution by 

 Provinces and by creameries of molds and 

 yeasts in the 93 Dominion Contest lots, 

 while Table IV shows the distribution of 

 molds and yeasts in 76 lots from seven rep- 

 resentative Ontario creameries and the Col- 

 lege creamery at the O. A. C, Guelph. 



Turning to Table II we note that the 

 number of Oidium colonies found are, on the 

 whole, fairly low, 63.4 per cent, of the 

 Dominion lots and 70 per cent, of the On- 

 tario lots giving counts of less than 10 

 colonies per c.c. Oidium counts of over 10 

 per c.c. show incomplete pasteurization, re- 

 contamination of the pasteurized cream with 

 raw cream, or recontamination from dirty 

 pumps, conductor pipes or churns. 



Yeast counts, it will be noted, run consid- 

 erably higher than the mold counts, 82.7 

 per cent, of the Dominion lots and 59.4 per 

 cent of the Ontario lots giving counts of 

 1,000 per c.c. or over. 



The first assumption might naturally be 

 that the pasteurizing temperature has not 

 been sufficiently high to destroy these or- 

 ganisms in the cream. This assumption, 

 however, is not justified^ because many of 

 the creameries showing high yeast counts are 

 heating their cream to 180° F. and holding 

 it at that temperature for 10 to 20 minutes. 



Neither will yeasts survive temperatures 

 which give a negative reaction when Storch 

 tests of the butter are made. 



Pockets of unheated or insufficiently heat- 

 ed creanl in pasteurizing apparatus occasion- 

 ally allow yeasts to survive, as will a drop 

 in temperature with a continuous pasteurizer, 

 or insufficient heating of cream at the be- 

 ginning or end of a run. 



Occasionally raw cream finds its way into 

 pasteurized cream, intentionally or accident- 

 ally, possibly through a leaky valve. Con- 

 ductor pipes and pumps through which the 

 pasteurized cream passes are not always as 

 clean as they should be. Cases have been 

 brought to our attention where the same 

 pump and pipes have been used indiscrim- 

 inately for handling both raw and pasteur- 

 ized cream without any washing in between. 



Any or all of these conditions will tend to 

 increase the yeast content of the butter to 

 some extent, but in creameries where high 

 yeast counts are the regular thing, our in- 

 vestigations indicate that nine times out of 

 ten the trouble is due to a yeast-infected 

 churn. 



The churn is the most insanitary piece of 

 apparatus found remaining in the modern 

 creamery. It is full of crevices and corners, 

 shelves, rollers, eye-glasses, bolt heads, stuff- 

 ing boxes, gates and doors, making it a dif- 

 ficult piece of apparatus to keep mechan- 



TABLE V. 



Distribution of Molds (oidium lactis) and Yeasts in 537 lots of Ontario creamery 

 butter, all Storch Test negative, season 1921. 



Oidium Counts 



per CO. Number of 



of butter Samples Per cent 



1— 



5— 



10— 



20— 



100 



500 







4 



9 



19 



99 



499 



999 



128 

 152 

 54 

 58 

 77 

 49 

 6 

 13 



1,000 — and over 



Yeast Counts 



per c.c. 



of Butter 



0— 99 



100— 499 



500— 999 



1,000— 4,999 152 



5,000—99,000 132 



100,000 — and over 54 



23.8 



28.3 



10.1 



10.8 



14.4 



9.1 



1.1 



2.4 



Number of 

 Samples 

 54 . . . 

 95 . . . 

 50 . . 



Per cent 



10.1 



17.7 



9.3 



, 28.3 



, 24.5 



10.1 



