Apr. 15,19x4 
Flavor of Roquefort Cheese 
9 
ORIGIN OF THE VOLATILE ACIDS OF ROQUEFORT CHEESE 
Neuberg and Rosenberg (12, p. 178) have shown that the volatile fatty 
acids may arise from the putrefaction of casein. From 1 kilogram of 
casein they isolated 40 grams of butyric acid, 95 grams of caproic acid, 
5.0 grams of capric acid, and a considerable quantity of valeric acid. 
More recently Neuberg (11, p. 501) has shown that putrefactive bacteria 
produce normal valeric acid from prolin and active valeric acid and 
active caproic acid from isoleucin. Valeric acid has long been consid¬ 
ered as a putrefactive product, and its occurrence in Limburger cheese 
accounted for in this manner. 
The flavor of Roquefort cheese gives no suggestion whatever of the 
products accompanying putrefaction. Since the volatile acids include 
those represented in milk fat from lauric to butyric and in about the same 
proportions as in milk fat, we are led to conclude that they arise from a 
hydrolysis of the fat. 
There is no conclusive evidence that the glycerids of fat are unequally 
attacked by lipolytic enzyms, and if the volatile acids result from a 
hydrolysis of the fat the insoluble acid number of the cheese fat should be 
about proportional to the volatile acid number of the cheese. This is 
shown to be the case in Table IV. 
The biological significance of the small quantity of acetic and possibly 
formic acid present is not clear. However, these may result from a fer¬ 
mentation of the carbohydrates in the early stages of ripening or may be 
a product of the partial oxidation of higher acids or glycerin by the mold. 
cultural studies of penicillium ROQUEFORTI 
No biological study ever reported has shown that any other organism 
than Penicillium roqueforii is essential to the proper ripening of this 
variety of cheese. Some of the proteolysis is to be attributed to the 
rennet, as is the case with all renneted cheeses, and the bacterial flora 
common to milk is responsible for the development of acidity in the curd 
during the early stages of ripening. The hydrolysis of the fat can 
hardly be ascribed to either of these agencies. So to obtain more defi¬ 
nite information concerning the action of P. roqueforti on butter fat, 
various cultural studies have been made. 
Czapek’s solution, with such modifications as will be specified, was 
sterilized with steam and used for all cultures on liquid media. 
Penicillium roqueforti will grow upon such a solution of inorganic 
salts as this medium contains when cane sugar is wholly replaced by 
pure butter fat, tributyrin, ethyl butyrate, glycerin, butyric acid, or 
ammonium butyrate. Therefore the mold not only has the ability to 
hydrolyze simple esters and triglycerids but also to utilize their constitu¬ 
ents as sources of carbon. This would presuppose the presence of a lipolytic 
enzym in the organism. Generally, the action of an enzym-containing 
extract of an organism is so much feebler than the action of the living 
