EXAMINATION OF BREAD 229 
bacteriologists. Russell (1903) examined a sample of slimy bread and 
isolated B. mesentericus vulgatus. Temperature studies indicated that 
the organisms could pass through the baking temperature. Watkins 
(1906) has studied the question and advised that the flour be subjected 
to examination when this infection appears. Kornauth (1912) also 
advised an examination of the flour for the organism. Williams (1912) 
found a capsulated organism in a case of slimy bread. Kayser, (1911) 
found that the bacteria causing this infection were introduced with the 
yeast. He stated that 1 to 2 liters of vinegar added to each 100 kg. of 
the flour would prevent the infection. Kayser and Delavel (1912) 
isolated bacteria which were related to the mesentericus group. When 
a bakery once becomes infected with members of this group, it is disin- 
fected with great difficulty. Kayser suggests the use of acidulated 
water for washing all of the apparatus and even states that some appa- 
ratus may have to be discarded. 
Wright (1916), when studying musty bread, found an Aspergillus 
and Rhizopus nigricans. Further experimental work indicated that the 
R. nigricans produced a mustiness in bread while Aspergillus produced 
asourness. It was believed that the mustiness resulted from proteolytic 
enzymes from the f. nigricans. 
Watkins’ Method for Detecting in the Flour the Organisms which Cause Ropy 
Bread. This author (Watkins, 1906) finds the followmg procedure a delicate one 
for determming whether a flour contains those bacteria which cause ropy bread. 
The test is rapid and the author states that there 1s little possibility of a sound 
failing to pass the test because they do not yield appearances of ropimess in the 
time proposed as a limit. Ten large test tubes (6 in. by 1 in ) are thoroughly boiled 
in water for one hour, washed and drained. When drained sterilize m the oven 
at 232° C. for three hours The tubes should be thoroughly sterilized. Cool 
and then place into each tube a finger of bread 3 in. by 3 in, cut from the center 
of the same two-day old loaf. The average weight of each loaf should be 5 gms. 
Moisten with distilled water and plug the tubes. Sterilize by boiling in water on 
three successive days. To test the flour, 2 gms. are well mixed with water and placed 
in boiling water for thirty minutes. To the series of ten tubes add successively 
from 1 to 7 cc. of the flour mixture, leaving three tubes to serve as checks. Number 
the tubes in rotation. Incubate at 28° C. and at the end of twenty-four hours 
examine for ropiness. 
Kornauth’s Method for Detecting Organisms in Flour which Cause Ropy 
Bread. This is a modificationof Kuhl’s method and is carried out as follows: 280 
gms. of flour, 140 c.c. of salt water, and 0.6 gm. of yeast are made into a loaf. 
After baking, the loaf should be stored at 25° C. for forty-eight hours. If the 
organisms causing ropy bread were present in the flour, the loaf will have a char- 
acteristic odor. Several loaves should be made at the same time with sound flour 
as a check. 
