SIXTH ANNUAL YEAR-BOOK — PART V. 427 



During the winter when sometimes the millc is permitted to stand in 

 the barn and absorb the barn odors, a great deal of the millv comes 

 to the creamery which lias this barn smell. This can also to a large 

 extent be eliminated by pasteurizing the cream. 



The second way by which uniformity is brought about by pasteuri- 

 zation is that it enables the buttermaker to control the fermentation 

 of the cream. When we pasteurize a sample of cream the most of the 

 germs are destroyed. All milk and cream contain a large number or 

 germs of different kinds; there are desirable germs, and undesirable 

 germs. When we pasteurize that cream we destroy most of these 

 germs, and when that cream is cooled down again and a good starter 

 is added, or a starter which contains desirable germs, at a favorable 

 temperature, we have favorable conditions for getting uniform results 

 every day. 



The second effect of pasteurization is that it improves the keeping 

 quality of the butter, and that improvement in the keeping quality of 

 the butter is quite an important thing at the present time, simply 

 because the storage of butter from the time of large supply and small 

 prices to the time of small supplies and higher prices is becoming a 

 very important thing, and for that reason it is very important for 

 creamery operators to manufacture butter which has good keeping 

 qualities, and it has been amply proven in practical work, as well as 

 through experimental work at our different experiment stations, that 

 butter made from pasteurized cream has much better keeping qualities 

 than has butter made from raw cream. That improved keeping quality 

 is simply due to the fact that when we pasteurize the cream we destroy 

 the germs, desirable and undesirable, most of them; when we have 

 added desirable germs by using a starter, so that when the cream is 

 ripened it contains germs of the deirable kind, and when that cream 

 is made into butter, none but the desirable germs are transferred to 

 the butter, that is providing the butter is not contaminated during the 

 process of manufacture, such as from impure wash water, unclean 

 churns, utensils, etc., but it is taken for granted that any buttermaker 

 who is able and qualified to carry on pasteurization properly knows 

 how to govern those other conditions as to not injure the keeping 

 quality of the butter. 



At the Iowa experiment station we carried on experiments to 

 demonstrate this phase of the subject; we found that butter made 

 from pasteurized cream and washed in pasteurized water kept in good 

 condition about seventy days, or ten weeks; butter manufactured 

 from the same quality of cream but raw, kept in good condition only for 

 about five weeks or about half the time. This butter was kept under 

 normal creamery conditions in a refrigerator at a tem^jerature between 

 60 and 70 degrees F. That illustrates that butter from pasteurized 

 cream will keep much better than butter from raw cream. In fact, I 

 think that is the strongest point in favor of pasteurization. 



Third, — I would say that the effects of pasteurization of cream is for 

 the improvement of the sanitary condition of the cream, the butter- 

 milk and also the butter. Now we often hear people say that certain 



