534 ^ Study of Ropy Bread [June 



ropiness more rapidly than do those made from very stiff doughs. 

 Nos. II, 12, and 13 were slow in developing ropiness because the 

 degree of infection was small, the temperature of incubation rather 

 low, and the moisture not excessive. Ropiness was here, as in the 

 other breads, first indicated by the odor. The usual ropy condi- 

 tion did not, however, develop, but the crumb became pink in the 

 infected bread. No rods were apparent. Watkins^ makes note of 

 an occasional development of a pink crumb accompanied by a ropy 

 smell. Lafar"* mentions a bacillus occurring in ropy bread which 

 gave a red color and was found to be harmless. 



Conclusions. From the above results the following conclusions 

 were drawn: 



1. Ropiness in bread is produced by a rather short, thick, slug- 

 gishly motile, rod-bacillus possessing a capsule; this bacillus is 

 found in some flours. Such rope-infected flour may also contain a 

 coccus capable of producing a pink crumb on and near the cut sur- 

 faces of the bread; a characteristic odor of rope precedes the ap- 

 pearance of color. Such a development does not ordinarily take 

 place, because it is slow, and ropiness develops first. 



2. Bread made from infected flour may be prevented from de- 

 veloping rope by keeping the bread dry and at a low temperature. 



3. Increased concentration of the bacilli in the flour and under- 

 baking produce an increased rapidity in development of ropiness. 



4. The stiff er the dough the more gradual the development of 

 ropiness. 



5. Butter-milk, if used as the liquid for mixing dough, will, in 

 some cases, prevent the development of ropiness. The amount of 

 butter-milk used must, however, be in proportion to the degree of 

 infection of the flour. A flour may be so strongly infected that the 

 exclusive use of butter-milk, of 0.7 per cent. acidity, will not prevent 

 the growth of rope. 



'Watkins: Jour. Soc. Chem. Indus., 1906, xxv, pp. 351-354- 

 * Lafar : Handbuch der technischen Mykologie, 1908, ii, p. 522. 



