148 REPorRT OF THE BACTERIOLOGIST OF THE 
per cu. cm. found by Dr. H. L. Russell® in 50 samples of milk 
pasteurized by the discontinuous method for direct consumption, 
the surprising thoroughness of this continuous pasteurization at 
80° ©. 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.) ina 
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 narrow 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 temperature well above that 
at which an active germ-killing effect begins. 
The strongest argument 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. 
6 Ann. Rept. Wis. Agr. Exp. Sta., 1895, p. 159. 
