204 
Journal of Agricultural Research 
Voi. II, No, 3 
This organism, as might be expected, shows a marked difference from 
the coccus group in the character of the substances formed. A large 
amount of lactic acid, including both the racemic and the active forms, 
was produced. All the citric acid of the milk was destroyed. Like the 
coccus forms, this organism also produced much acetic acid, but no 
formic, butyric, or caproic acid. Culture 583 produced some esters. 
ESTER FORMATION IN CHEDDAR CHEESE 
It has been determined that esters do not appear in Cheddar cheese 
until it is about 5 weeks old. Streptococcus b 3 (see Table V) produced 
an ester content in the medium equivalent to 64.8 c. c. N/10. To throw 
some light on the question whether esters could be formed in the cheese 
or medium from mere mass action of free alcohol and acid, a trial was made 
with a mixture of these two substances. It is known that the contact of 
acetic acid and ethyl alcohol can produce esters even without adding a 
dehydrating agent. Dilute solutions of pure acid and pure alcohol were 
mixed and allowed to stand for a few months, and then a very slight 
excess of KOH solution was added. The alcohol and esters were next 
distilled off. The distillate was saponified with KOH, acidified with 
H 2 S 0 4 , and distilled repeatedly to obtain the acids which had entered 
into the ester combination. Blank determinations were carried out to 
check the purity of all chemicals used. The results are given in Table 
XIII. 
Tabl,E XIII .—Production of ester from the contact of acid and alcohol 
Ethyl alcohol. 
Acetic acid. 
i 1 
Result. j 
1 ! 
1 
Per cent . 
I 
Per cent. 
I 
! 
No ester detected. 
2 
2 
Small amount of ester. 
5 
5 
Esters formed. 
. 8 1 
8 
Do. 
14 | 
J 
14 ! 
i 
Do. 
Table XIII shows that free acetic acid and alcohol can not form esters 
in dilute aqueous solutions. Comparing this concentration with that found 
in cheese, it is probable that the solution of alcohol in the cheese mois¬ 
ture is very dilute—much less than 1 per cent. The greater part of the 
acids is also combined with basic substances. If these assumptions are 
accepted, then it can be said that the esters in cheese are probably not 
produced by mere contact of alcohol and acid but by the intervention of 
biological activities. 
Of course, the question of actual concentration of alcohol or acid in 
any phase in the cheese mass is not possible of definite statement. There 
may be very little “free” water in the cheese, most of it being in com- 
