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E. B. FRED AND W. H. PETERSON 



was the same as in the previous experiment. Table 2 gives 

 the general plan and results of this test. The data recorded 

 in the table show: first, the close relation between amount of 

 sodium chloride and formation of pink sauerkraut; second, the 

 decided influence of temperature on color. These two points are 

 so clearly brought out in the table that a detailed explanation is 

 not needed. The findings are in accord with the observations of 

 kraut manufacturers ; namely, that high salt concentration may 

 cause pink sauerkraut. 



TABLE 3 



Effect of sodium chloride on the ■production of acids by lactic acid bacteria; 



calculated for 100 cc. of culture 



An explanation for this condition may be found from a study 

 of pure cultures of yeasts and bacteria common to sauerkraut. 

 Yeasts can live in the presence of high concentrations of salt while 

 the bacteria commonly associated with kraut are not so resistant. 

 Support for this statement is given in the figures of table 3. Here 

 the influence of varying amounts of sodium chloride on a pure 

 culture of lactic acid bacteria was studied. This lactic acid 

 organism was isolated from normal sauerkraut. About 4 per cent 

 of salt is the critical concentration for this organism. 



Orla-Jensen (1919) has carried out an extensive study of the 

 influence of sodium chloride on acid production by various types 

 of lactic acid bacteria. He found that the conmion forms of 

 lactic acid bacteria, the Bacterium ladis-acidi, Lactobacillus 

 bidgaricus, and other tjiies are slightly retarded by 2.5 per 

 cent of salt. On the other hand, certain of the rod forms of lactic 



