392 BACTERIA IN OTHER FOODS 



milk is sterilized after sealing, and hence when properly done the 

 finished product should contain no bacteria. The organisms which 

 at times survive pasteurization and later may cause spoilage are 

 B. subtilis, 11. mesentericus, and B. ctxiytiltinx. 



The degree of heat to which all the condensed, concentrated, and 

 powdered milk are subjected is probably sufficient to kill all tubercle 

 bacilli and typhoid bacilli, but Andrews' work would indicate that 

 at times condensed milk may act as a differential medium for 

 Staphylococci. He reports instances where at time of condensation 

 a few Staphylococci Pyogenes aureus were present, but later when the 

 cans were opened many were present. 



Bacteria in Bread. The interior of the loaf reaches a temperature 

 of 101 to 103 C. and the crust 125 to 140.5 C. in the baking 

 process; hence only the more resistant sporebearing organisms 

 would survive the baking process. Disease germs, therefore, seldom 

 -if ever occur in the freshly baked bread. However, B. mesen- 

 tericus vulgatus, and probably other organisms which cause slimy 

 or ropy bread, may survive and cause considerable economic loss. 



When they have found their way into a bakery the ease with 

 which they are overcome depends upon whether they are in the 

 yeast, on the utensils, or in the flour. If they are in the yeast, a new 

 start must be obtained, and Kayser suggests the use of acidulated 

 water for washing all of the apparatus and even states that some of 

 the apparatus may have to be discarded. Great economic loss, 

 however, results when the flour is the infected material. 



Although bread is free from pathogenic bacteria when it leaves 

 the oven, this is often not true when it reaches the consumer, for 

 unwrapped bread must ever remain a constant danger. But when 

 once wrapped, the danger is not as great, for the wrapper acts as a 

 protection and if carelessly handled tells the tale to such an extent 

 that it may be refused by the consumer. 



Bacteria in Eggs. All investigators have found more bacteria 

 in the egg yolk than in the egg white, and many of those who have 

 found no bacteria in egg white have assumed that this part of the 

 egg possesses a bactericidal action. Rettger considers that the 

 contents of normal fresh eggs are as a rule sterile, although he con- 

 siders it quite probable that an egg yolk may become invaded before 

 it is expelled from the ovary. But this he considers an uncommon 

 occurrence, except when the ovary is infected with the organism 

 of bacillary white diarrhea. 



The percentage of infected eggs found by different investigators 

 as reported by Tanner is given below : 



Number Per cent. 



Author. examined. infected. 



Rettger 3516 9.5 



Rettger (10 c.c. samples) 647 3.86 



Bushnoll and Mauer 27.59 23.70 



Mauer 600 18.10 



Hadloy and Caldwell 2520 8.70 



