June, 1922 



SCIENTIFIC AGRICULTURE 



337 



TABLE VI. 



Showing correlation of Yeast and Bacterial content of 13 samples of Ontario Creamery 

 butter, season 1921. 



Yeast Content Average Bacterial 



Number of Samples per c.c. Content per c.c. 



6 10 — 80 36,583 



10 110 — 880 96,750 



15 1,100 — 5,000 791,300 



6 12,700 — 80.000 2,712,000 



6 100,000 — and over 6,897,000 



ically clean. Being made of wood it is 

 porous and, therefore, difficult to keep bac- 

 teriologically clean. Yeasts and other or- 

 ganisms get down into these pores and sur- 

 vive destruction when the churn is washed 

 and scalded in the usual way. Even a thor- 

 ough washing with chloride of lime solution 

 is not effective, according to our experience, 

 in eliminating yeasts from a yeast-infected 

 churn. Stuffing boxes, where the pins of 

 the worker rollers pass through the head 

 of the churn, are frequently hotbeds of in- 

 fection as may be readily shown by making 

 a culture of the salve-like material which 

 oozes out from them. 



During the time which elapses between 

 the washing and draining of a churn on one 

 day and of its use a day or two later, con- 

 ditions are frequently ideal in the pores of 

 the wood for an abundant growth of yeasts. 

 The acid reaction which becomes established 

 in the wood due to frequent contact with 

 sour cream is particularly favorable. Suffi- 

 cient food supply and moisture remain, while 

 air is available at the surface of the pores, 

 and an ideal temperature for growth usually 

 obtains. The hurried so-called "scalding" 

 which a churn receives just previous to run- 

 ning in the cream does not eliminate the 

 yeasts which have accumulated over night, 

 and after a few revolutions in such a churn 

 we find that our pasteurized yeast-free cream 

 contains numerous yeasts. 



The follownng facts have also been noted: 



1. Butter made from properly pasteur- 

 ized cream in a new churn is usually low in 

 yeast content. 



2. Where two or more churnings a day 

 are made in the same churn, butter from the 

 first churning will almost invariably contain 

 the largest number of yeasts. 



3. If a churn stands idle for several days 

 the yeast content of butter made in it when 

 brought into use again will usually be 

 high. 



4. Repacking of the boxes where the 

 worker roller pins pass through the head 

 of the churn frequently results in a reduc- 

 tion of the yeast content of the butter, some- 

 times to a very marked degree. 



The following method for treating yeast- 

 infected churns has been used by us effect- 

 ively (see Table IV, O.A.C. Creamery), and 

 has resulted in the reduction of the yeasts 

 in the butter to less than 10 per c.c: 



Rinse out the churn after use with hot 

 water and give a thorough washing with a 

 hot solution of alkali washing powder to 

 remove grease and to neutralize the acid 

 which has soaked into the wood while churn- 

 ing the sour cream. Secure a few lumps of 

 fresh unslaked lime and slake by adding 

 small quantities of hot water from time to 

 time. When slaked add sufficient hot water 

 to make up to ten gallons or so. Mix well 

 and pour into churn. Turn steam hose into 

 this milk of lime mixture and bring to the 

 boil. Close churn doors and revolve for fif- 

 teen minutes, five minutes at high speed, 

 and ten minutes at low speed with worker- 

 rollers in gear. Stop churn, turn in steam 

 hose and bring milk of lime mixture to the 

 boil again. Revolve fifteen minutes more as 

 above. Do not dump out lime mixture but 

 turn churn doors to top and fill to the brim 

 with cold water. Allow churn to stand full 

 of this lime water until required for use 

 again. Empty out lime water, wash out 

 thoroughly with two changes of cold water, 

 and the churn will be found to be practically 

 yeast-free. Where churns are in daily use 

 the above treatment should be applied once 

 a week, preferably over the week-end. Where 

 churns are to stand idle for some time they 

 should be treated as above and left filled 

 to the brim with the diluted milk of lime. 

 The stuffing boxes around the worker-roller 

 pins should be repacked from time to time, 

 or, as has alreac^y been mentioned, serious 



