532 /^ Study of Ropy Bread [June 



an increase in the concentration of bacilli in the flour, together 

 with underbaking, increase rapidity of development. It is also seen 

 that even when bread is made from infected flour, it is possible to 

 prevent the growth of rope by dryness and low temperature after 

 baking. 



Experiment 2. The aim of this experiment was to devise a 

 method of prevention that would be of practical use for the house- 

 wife. 



Procedure. Flour was thoroughly inoculated by the transfer- 

 ence of large portions of rope-infected bread to the flour. The 

 mixture was subsequently incubated in a moist Chamber at 50° C. 

 for 48 hours. At the end of this time a portion of the flour was 

 dried for 48 hours at 50° C. ; a portion was sunned in a thin layer 

 for 48 hours; and the remainder was made into breads, with hop- 

 water and with different proportions of buttermilk. The acidity 

 of the buttermilk used was 0.7 per cent. Table 3 shows the results 

 of the baking experiments. 



Discussion of the results. Within the limits of this experiment, 

 sunning and drying of flour had no effect upon the bacillus that pro- 

 duced rope; neither did hop-water seem to be effective. 



The results obtained by the use of different concentrations of 

 bacilli in the flour, and of butter-milk, showed that when the entire 

 loaf was made of the very strongly infected flour, even the exclu- 

 sive use of butter-milk of 0.7 per cent. acidity as the liquid for mix- 

 ing, failed to inhibit, or even retard noticeably, the development of 

 rope. When a very small portion of infected flour was present in 

 the bread, however, development of rope was slower; and the exclu- 

 sive use of butter-milk, as the liquid for mixing, inhibited all growth 

 of the rope; smaller quantities of butter-milk were, however, not 

 effective. It seems, from these results, that the use of butter-milk 

 in bread may be an effective preventive of rope, but the amount of 

 butter-milk must be in proportion to the degree of infection of the 

 flour. A flour may be so strongly infected, however, that the 

 exclusive use of butter-milk will not prevent the growth of rope. 



The breads in this experiment were all of excellent texture and 

 of good flavor. A comparison of Nos. 6 and 7 shows that breads 

 made from soft doughs, hence containing more moisture, develop 



