YEASTS AND OIDIA IN PASTEURIZED BUTTER 133 
of raw spontaneously soured cream always contained from 
10,000 to 100,000 yeasts (per ec. ¢.) and not quite so many 
Oidia. In the winter the numbers are smaller with the Oidia 
often preponderating. Properly pasteurized cream, right 
from the pasteurizer, never contains yeasts or Oidia. Here, 
then, is the test for pasteurized cream and pasteurized butter ! 
But cream off the cooler, in the cream vat, in the churn, and 
the resulting butter, showed many veasts and Oidia. The 
first and last cream issuing out of flash pasteurizers was not 
pasteurized and had to be diverted by a by-pass till a pasteur- 
izing temperature had been reached and maintained for sev- 
eral minutes. The last cream had to be heated in a can or 
held over till the next pasteurization. The outlet of re- 
tarding and pasteurizing vats formed a long pocket in which 
cream escaped pasteurization. This pipe was shortened. Raw 
cream dripped into the pasteurized cream from pipes and 
conductors that had conveyed the raw cream. These were 
removed. Raw cream splashed upon the sides and cover of 
a vat escapes pasteurization and is usually washed into the 
churn with the hose. This is partly overcome by rinsing with 
hot water or hot cream during pasteurization. 
No amount of scrubbing of utensils or pipes will produce 
good bacteriological results. This must be completed by 
sterilizing by means of hot water or live steam. Permanent 
steam connections on cream pipes give the best results. The 
packing glands of vats, pumps, and churns and the wood of 
churns, as they are today, are difficult to sterilize and furnish 
some of the yeasts and Oidia. Sometimes the starter becomes 
contaminated and introduces yeasts and Oidia. It is easy to 
see how laymen handling both raw cream and pasteurized 
products may contaminate the latter with their hands, ther- 
mometer, dipper, and measuring stick. 
In December, 1912, in one plant we began yeast and Oidia 
counts in a eubie centimeter of butter. The totals ranged 
from two to fifty. In August, 1913, the counts declined to 
ten or less. We continued improving methods and equip- 
ment and educating the men, and by July, 1916, we reduced 
the counts to zero to five. This efficiency is now main- 
