626 MILK 



Blue cheese occurs sometimes as a result of bacterial action 

 or from a chemical process. If the whole surface is covered, it 

 is due to a chemical process resulting from the use of iron vessels. 

 The lactic acid takes up some of the iron, which is then precipi- 

 tated as a dark blue substance, with the evolution of some hydro- 

 gen sulphid. Copper from copper vessels also may dissolve and 

 cause coloration of the cheese. Blue spots are sometimes caused 

 by Bacillus cyanofuscus, which occurs in surface waters. Iron 

 bacteria also may cause the formation of bluish-black spots. 



As a carrier of disease germs cheese is not very important. 

 As a rule, cheese is consumed after a long period of ripening, and 

 pathogenic bacteria do not survive exposure to adverse conditions 

 such as are found in cheese making. The acid and the competition 

 of enormous numbers of saprophytic micro-organisms act un- 

 favorably on disease germs. Mohler, however, has stated that 

 tubercle bacilli were found in Cheddar cheese when fom' months 

 old. There is some menace to health in cheese which is con- 

 sumed fresh, such as cottage cheese, for example. Pasteurization 

 of the milk used for this class of cheeses is, therefore, advisable. 



Schroeder and Brett express their opinion of the possible in- 

 fectiousness of cheese in the following words: 



"1. We may safely say, and we say it with great satisfaction, 

 that cheese of the kind which requires some time to ripen rarely 

 if ever contains true living, pathogenic bacteria when it is mar- 

 keted, and it does not seem likely that such cheese is apt to con- 

 tain dangerous products of bacterial origin. 



"2. Cream cheese, which is an elegant, palatable, nutritious 

 article, recommended by many physicians as excellent food for 

 children and invalids, until quite recently was heavily contami- 

 nated with tubercle bacilli of the bovine type, or tubercle bacilli 

 of the kind which have their origin in the bodies of tuberculous 

 cattle." 



Poisoning after the consumption of cheese has been reported. 

 The symptoms are nausea, vomiting, and diarrhea, followed by 

 general weakness. There are different theories as to the cause 

 of such sickness. In a few cases a poison has been found in the 

 cheese, and this was called tyrotoxin (Vaughan and Perkins). 

 In other cases the origin of the poison was ascribed to strains of 

 Bacillus coli which were held responsible for diarrhea in cows and 

 which gained access to the milk. Again, it has been beheved that for- 

 mation of ptomains, such as putrescin and cadaverin, or formation 

 of hydrogen sulphid and indol have been responsible for poison- 

 ing. These substances are not supposed to be intensely poison- 

 ous and are probably the cause of untoward symptoms only when 

 real putrefaction has taken place, so that they are present in rela- 



