208 
Journal of Agricultural Research 
Vol. II, No. 3 
Table XVII shows that the whey and curd contained active lactic 
acid and had a similar course of fermentation during the very early 
stages. A different fermentation evidently took place in the cheese 
after pressing, but not in the curd stage. The next question that arose 
was, At what stage in the curing process did the production of racemic 
lactic acid take place? The data in Table XVIII show that racemic 
acid begins to appear very soon after going to press. 
TablH XVIII .—Analysis of whey , curd, and cheese , showing the quantity of lactic acid as 
zinc lactate 
Fraction No. 
j | 
Whey when 
drawn. 
Curd at hoop¬ 
ing time. 
Whey kept at 
temperature of 
curd and stood 
overnight in 
pressing room. 
Cheese 24 hours 
old. 
Cheese 48 hours 
old. 
Crys¬ 
tals of 
zinc 
lactate. 
Water 
of 
crys¬ 
talliza¬ 
tion. 
Crys¬ 
tals of 
zinc 
lactate. 
Water 
of 
crys¬ 
talliza¬ 
tion. 
Zinc 
lactate. 
Water 
of 
crys¬ 
talliza¬ 
tion. 
Crys¬ 
tals of 
zinc 
lactate. 
Water 
of 
crys¬ 
talliza¬ 
tion. 
Zinc 
lactate. 
Water 
of 
crys¬ 
talliza¬ 
tion. 
1. 
Grams. 
0.2360 
. 0000 
Per ct. 
13.64 
Grams. 
0.3044 
.0000 
Per ci. 
13.00 
Grams. 
0.6435 
.8010 
*2 745 
.3863 
.2788 
.0975 
Per ct. 
13-05 
33*54 
33*47 
12 .96 
I3‘ 32 
33*53 
Grams. 
0.0533 
,0846 
. 1260 
. 2606 
• 4948 
Per ci. 
17.07 
37*37 
37 . 77 
14. 39 
13*29 
Grams. 
0.1123 
. 1420 
•5805 
*0565 
*4555 
Per ct. 
37*45 
17.11 
17.07 
14.69 
* 13.63 
2. 
5... 
6. 
Whey when drawn, and also after standing overnight, contained 
active lactic acid. Curds at hooping time contained active lactic acid. 
One-day-old and two-day-old cheese contains a mixture of racemic and 
active acid. 
The causes for the early production of racemic acid and the disappear, 
ance of active acid may be ascribed to a direct production by either 
enzyms or bacterial action of active acid which is of opposite polarity 
from that already present. 
In order to study the relation of enzymic action in curd to this prob¬ 
lem, the following experiment was performed: Curd at hooping time 
was divided into five parts. The first portion was immediately analyzed 
for lactic acid; the second portion was analyzed after standing 46 hours 
in the pressing room; the third portion was kept for 17 days at 35 0 C.; 
the fourth part was treated with chloroform and kept for 17 days at 
room temperature; the fifth portion was treated with chloroform and 
stood for 3 months at room temperature. The data secured on the 
nature of the lactic acid produced are shown in Table XIX. 
