2 
Journal of Agricultural Research 
Vol. II, No. i 
456), found small quantities of alcohols and esters in the neutral “flavor 
solution” obtained from Cheddar cheese. 
The neutral flavor solution from 750 grams of a ripe Roquefort cheese 
was studied, using the method outlined by the above-mentioned inves¬ 
tigators. The acids in ester combination in this large mass of cheese 
totaled only 0.44 decinormal c. c. It is hardly possible to identify 
accurately the acids of a mixture so small in quantity. The propor¬ 
tional numbers obtained by a Duclaux distillation approximated the con¬ 
stants for acetic acid. The odor of Roquefort cheese suggests ethyl 
acetate, and this ester may be partially responsible for the typical 
aroma, but it is doubtful whether the quantity is large enough to mate¬ 
rially influence the taste. 
As early as 1877, Nencki (10, p. 1033), attempted to isolate the sub¬ 
stance giving to Roquefort cheese its piquant taste. He acidified about 
one pound of cheese with sulphuric acid and distilled it with steam. After 
filtering the distillate he neutralized it with sodium hydroxid and extracted 
it with ether. After evaporation the ether extract left a “very volatile, 
slightly yellow-colored oil of sharp burning taste, neutral reaction, and 
characteristic moldy odor.” The quantity of this oil was not sufficient 
for identification. 
Repeated attempts with the ripest cheese procurable were made to 
duplicate the results of Nencki. Very small quantities of a gummy white 
mass were obtained, which consisted chiefly of the sodium salts of butyric 
and caproic acids. Although the oil described by Nencki was not found 
by following his procedure, it was observed that globules of an insoluble 
oil floated upon the surface of the distillate. This oil, which Nencki 
apparently filtered off and discarded, was identified as a mixture of the 
volatile and soluble acids of milk fat. The amount of these insoluble 
acids increased with the ripeness of the cheese distilled and appeared to 
be a normal product of the curing process. Since these acids possessed 
a peppery taste and the cheese mass after distillation was almost taste¬ 
less, a detailed study of their origin and relation to the flavor of the 
cheese was made. 
EXPERIMENTAL METHODS EMPLOYED 
Typical Roquefort cheeses of various stages of ripeness were purchased 
in the retail markets and used in these experiments. In general, the 
method of study outlined by Jensen was followed. 
After scraping off any slime on the surface of the cheese, a wedge-shaped 
section extending from the periphery to the center was cut out, minced, 
and thoroughly mixed. A sample of 50 to 150 grams, depending on the 
ripeness of the cheese, was weighed, rubbed to a smooth cream with warm 
water in a mortar, and rinsed into a 500 c. c. Kjeldahl flask. The sus¬ 
pension was made up to a volume of 250 c. c. of dilute sulphuric acid 
added in slight excess, as indicated by a blue color with Congo red, and 
