148 Repoet of the Bacteeioloqist of the 



per cu. cm. found bj Dr. II. L. Russell" in 50 samples of milk 

 pasteurized by the discontinuous method for direct consumption, 

 the surprising thoroughness of this continuous pasteurization at 

 80° C. will be understood. 



Were it not for the fact that in the present state of our knowl- 

 edge it is believed that a heating of milk to 85° C. (185° F.) in a 

 continuous pasteurizer is necessary to remove all danger of tuber- 

 culosis, the use of 80° C. in pasteurization for butter-making, at 

 least in this special machine, would leave little to be desired. 



Confining our attention to the number of germs found in the 

 pasteurized milk, the results of the above tests show that there 

 is practically no increase in efficiency in passing from 80° C. to 

 85° C. If we can be allowed to generalize on so naii'ow a basis 

 as seven determinations the gain comes in an increased regularity 

 in the reduction of the number of germs present. There is also 

 a practical advantage in working at a temperatm*e well above that 

 at which an active germ-killing effect begins. 



The strongest arg-ument in favor of 85° C (185° F.) lies in the 

 fact that it is the lowest one that we can use and feel assured that 

 we have removed the danger of returning germs of tuberculosis 

 along with the mixed skim milk from the factory. Leaving out 

 of account all relation of this disease to the human family, its effect 

 upon our calves and pigs is one that we cannot afford to ignore. 



While it does not come within the province of this bulletin to 

 discuss the effect of heating upon the butter, it will not be out 

 of place to state that, even with cream from milk which had been 

 heated to 85° C, butter was made in which no cooked flavor could 

 be detected when coming from the churn. While our efforts were 

 not universally so successful, still, in the cases where such a flavor 

 was noticeable at churning, this disappeared after a few hours 

 standing. The experience of this Station, so far as it goes, is quite 

 in accord with that of Dr. Storch, who states that whole milk can 

 be heated to 90° C. without any permanent injury to the flavor 

 of the butter. 



« Ann. Rept. Wis. Agr. Exp. Sta., 1895, p. 158. 



