DAIRY FARMING DAIRYING. 889 



The question whether they are harmful to human beings will be a mat- 

 ter for further investigation. « 



Pasteurization as applied to butter making, 1". II. Farrington 

 and H. L. Russell ( Wisconsin Sta. Bui. 69, pp. 10, figs. 3). — The bulle- 

 tin gives briefly the history of the use of pure cultures in butter making 

 and describes a series of experiments, extending from February to 

 August, which were made at the creamery of the Wisconsin Dairy 

 School. Where pasteurization was practiced, the milk and not the 

 cream was pasteurized. In 74 trials the milk was divided, a part being 

 pasteurized, while the rest was used in the ordinary way. In addition 

 to this the entire quantity of milk was pasteurized on certain days and 

 on other days was used without pasteurizing. There were 110 cases of 

 this kind. The unpasteurized milk was heated to about 85° for sepa- 

 rating, while the pasteurized milk was heated to 155° F. in a Eeid con- 

 tinuous pasteurizer. The cream was nearly always ripened with a 

 starter made from the Boston butter culture, a pure culture of Micro- 

 coccus butyri aroma faciens. The other operations were similar to the 

 ordinary methods of creamery butter making. The butter was scored 

 twice by a butter expert in Chicago, the first time within 2 weeks after 

 making. The second scoring for flavor was made several weeks later. 



The culture starter was always found to be free from all foreign 

 organisms, and it was demonstrated that practically sterile skim milk 

 for the purpose of propagating the starter could be easily obtained in 

 general creamery practice. 



As to the efficiency of the sterilizer used, 13 samples of milk before 

 heating showed an average of 32,000,000 bacteria per cubic centimeter, 

 while the average of 1G samples after pasteurizing showed 1,800,000 

 bacteria, or a reduction of 91 per cent. As compared with an intermit- 

 tent pasteurizer, the number of germs in the pasteurized milk is much 

 larger. 



The skim milk from the pasteurized milk kept from 12 to 24 hours 

 longer than that from the unpasteurized milk, and in some cases was 

 sweet after 48 hours. 



The data for the butter making on 4 days in each month are tabu 

 lated, together with the scores of the butter made from pasteurized and 

 unpasteurized milk, the scoring as affected by the size of the package, 

 maximum, minimum and average composition of the butter from pas- 

 teurized and unpasteurized milk, efficiency of creaming milk heated to 

 85° and lf>5° F., and the churning record for the jKisteurized and 

 unpasteurized butter during the hot weather. 



"A comparison of tho flavor scores of 102 churnings of fresh unpasteurized butter 

 with those of 75 of pasteurized butter shows the average score of each to be very 

 uearly the same (^40.69 unpasteurized, 40. H3 pasteurized) on a basis of 45 as perfect 

 flavor, but 5 per cent more of the unpasteurized than the pasteurized butter scored 

 42 points or better. 



"The difference in the fresh scores is so slight that it is impossible from these 

 scores to conclude that one system produces higher flavor than the other. The 



