May 15, 1925 
Fermentation of Sauerkraut 957 
counts by the Breed plate method. 
The formation of clumps makes it 
difficult to determine the number of 
single cells. In many cases clumps 
of bacteria may have been counted 
as one cell (Table II). 
Table II .—Number of bacteria in 
sauerkraut as obtained by the direct- 
count method 
Age 
Number of bacteria in 
1 c. c. of brine 
Uninocu¬ 
lated 
Inoculated 
Days 
Thousands i 
Thousands i 
3_ 
55,000 
60,000 
85,000 
5_ 
80,000 
7_ 
105,000 
145,000 
12_ 
115,000 
125,000 
21_ 
30_ _ 
110,000 
120,000 
125,000 
73_ 
50,000 
50,000 
1 Thousands—i. e., 000 omitted. 
The examination of the Breed plates 
showed, first, a change in the ratio be¬ 
tween the types of organisms present 
in sauerkraut at different times dur¬ 
ing the fermentation; second, a dif¬ 
ference in the flora of the inoculated 
and uninoculated krauts. During the 
early part of the fermentation period 
the inoculated kraut showed about 
equal numbers of short rods and 
coccus forms, while the uninoculated 
kraut contained more rods than coccus 
types. During the course of the fer¬ 
mentation the number of coccus forms 
decreased in relation to the number 
of rod forms. This decrease was most 
rapid in the uninoculated kraut. The 
short rods were later replaced by a 
long rod which was the predominating 
organism at the end of the fermenta¬ 
tion. There was very little difference 
in the appearance of the flora of the 
uninoculated and inoculated kraut 
at the end of the fermentation, because 
the coccus forms had practically dis¬ 
appeared in both cases. 
DETERMINATION OF THE NUMBER AND 
KIND OF BACTERIA BY MEANS OF 
SUGARS 
Each time when the vats were 
opened, a small quantity of brine was 
removed from the vats with a sterile 
pipette and placed in a sterile flask. 
The brine was carried through a series 
of eight dilutions extending from 1 
c. c., diluted to 100, to 1 c. c. diluted 
to 1 billion. From each of these 
dilutions 1 c. c. was transferred to a 
tube containing 10 c. c. of sterile 
yeast water and 0.5 per cent of one of 
the following compounds: Glucose, lac¬ 
tose, xylose, and mannitol. Besides 
the sugar media, two sets of tubes con¬ 
taining litmus milk were also inocu¬ 
lated in the same manner. One set of 
tubes of litmus milk was heated after 
inoculation to 80° C. for 10 minutes, 
and then melted vaseline was poured 
into the tube. All of the tubes were 
incubated for 96 hours at 28° C. Ob¬ 
servations were made for turbidity 
and gas production after 24, 48, and 
96 hours after inoculation. The high¬ 
est dilution in which there was turbidity 
or production of gas was taken as the 
number of organisms present which 
would ferment that particular sub¬ 
stance. After 96 hours the tubes were 
kept at room temperature, approxi¬ 
mately 20° C., for 10 days, and at 
the end of this time the total acidity 
was titrated with 0.1 N NaOH. 
The litmus milk tubes with vaseline 
plugs were made to determine if any 
spore-forming, gas-producing anaero¬ 
bes were present. Since no gas was 
produced and the litmus milk was not 
reduced or curdled, it is believed that 
none of the above group of organisms 
was present in the kraut. 
Table III has been compiled from 
more than 300 observations and shows 
the number of organisms in 1. c. c. of 
brine that will ferment some of the 
common sugars, mannitol, and litmus 
milk. The rate of increase and de¬ 
crease in the number of organisms is 
expressed in the same table. 
It will be noted that the number of 
bacteria which ferment any of the sub¬ 
stances used increases rapidly during 
the first 7 days of the fermentation and 
then decreases. The number of manni¬ 
tol fermenters is much less than the 
number of sugar fermenters at the 
height of the fermentation, but to¬ 
ward the end of the fermentation the 
numbers are approximately equal. 
The enormous number of xylose fer¬ 
menters present in the kraut at the 
height of the fermentation shows the 
importance of these bacteria in kraut 
formation. The influence of inocula¬ 
tion is indicated by the smaller number 
of xylose fermenters found in the in¬ 
oculated kraut. This is to be expected 
because the lactic bacteria used to in¬ 
oculate the kraut do not ferment 
xylose. 
The figures for litmus milk show that 
the lactic acid organisms increase 
much more rapidly in the inoculated 
than in the uninoculated kraut, and 
that they are present in much greater 
52205—25f-5 
