Origin of Butter Flavors 197 
lactic acid in ripening, Tiemann* found that in cream 
to which a small amount of hydrochloric acid had 
been added there was no difficulty in churning the 
butter, that the general flavor of the butter was 
good, but that it lacked in aroma and had a some- 
what oily texture. 
There is some doubt as to the origin of the 
characteristic flavors which are developed in the cream 
during the ripening process. These flavors are un- 
doubtedly due to the presence of certain volatile sub- 
stances—fats, bacterial products, or ether-like com- 
pounds—which are formed during the ripening pro- 
cess. It was formerly supposed that the production 
of the characteristic flavors was almost wholly a pro- 
cess of oxidation, and that cream, in order to be prop- 
erly ripened, and to develop the best flavors, must be 
supplied with an abundance of oxygen in pure air 
during the process. Our knowledge of the presence of 
germs in milk and cream and the effect of their 
growth upon the various constituents of the milk, has 
led us to modify these views. At the present time it 
seems probable that the growth of germs which pro- 
duce lactic acid has much to do with the production 
of the characteristic flavors of ripened cream. It has 
been asserted by some, notably Conn, that the produc- 
tion of the flavors is due to the growth of specific 
flavor-producing germs that are largely independent of 
the formation of lactic acid, but this view does not 
seem to explain all of the phenomena of the appear- 
*Milch Zeitung, xxiii p. 701. 
