438 
Journal of Agricultural Research 
Vol. XI, No. 9 
age, in order to study the effect of varying methods of manufacture and 
storage upon the keeping qualities of the butter. From time to time 
studies of the bacterial development in the stored butter were made. 
The results of this work have recently been published elsewhere (25). 
Since the conditions of manufacture and the bacterial development 
in these butters were known, they afford excellent material for a study 
of the enzym content of the butter after storage, and such a study was 
accordingly undertaken. 
REVIEW OF PREVIOUS WORK 
The following types of enzyms have been reported to be normally 
present in cow's milk: an amylase (27), a lipase (9), proteases (r-5, 7, 22) 
a peroxidase (19), salolase (22), catalase (72, 18 , 20), reductase (20), 
and a lactose-fermenting enzym (21). Vandevelde (22), however, 
concludes that no lipase can be found in fresh milk and that salolase is 
present in only very slight amounts; while Grimmer (jo), as a result of 
his study of the enzyms of the mammary glands, concludes that salolase, 
peroxidase, and catalase are the only enzyms which are normally secreted 
with milk. Further, Van de Velde and Landsheere (25) found no 
amylase in milk and criticize Spolverini's observations concerning 
peroxidase in milk, holding that its presence there is due to bacterial 
contamination. 
These reports indicate something of the confusion which exists 
with reference to the normal enzyms of milk. The contradictory evi¬ 
dence which has been presented undoubtedly results, in part at least, 
from the rather crude methods of study of enzym action which were in 
use at the time when these investigations were in progress. Unfortu¬ 
nately, little attention has been given to these matters during recent 
years, when more refined methods of study might have given more 
concordant results. 
The question as to whether any enzyms which may be present in 
milk will be carried down with the butter in churning has not been 
generally discussed. Kooper (13) states that during butter making 
catalase remains behind in the buttermilk and is therefore not a direct 
constituent of butter fat. It might be assumed, however, that any 
buttermilk which remains in the butter would contain the same enzyms 
that were present in the original mil^k. In fact, Hesse (72), who found 
small amounts of catalase in butter, calculated his results on the basis 
of its buttermilk content. Furthermore, since butter fat is undoubtedly 
an emulsion colloid, it might be assumed to carry with it into the butter, 
in the form of absorption complexes, large proportions of the enzyms 
originally present in the milk. But no definite information concerning 
these matters, other than that cited in the opening paragraphs of this 
paper, has been published. 
