412 EXPERIMENT STATION RECORD. 



The origin of the catalase in milk and its significance for the control of 

 the milk supply, A. Faitelowitz {MUclnv. Zentbh, 6 {1910), Nos. 7, pp. 299- 

 316; 8, pp. 361-381; 9, pp. ^20-427).— According to the author the most certain 

 and rapid method for estimating the catalytic activity of milk is by use of the 



formula C=-/| — ^ )• where t is the time, a the number of cubic centimeters 

 t \a—xj 



of oxygen in the hydrogen peroxid originally taken, and x the cubic centimeters 



of oxygen in the hydrogen peroxid evolved. This value in fresh unneutralized 



milk fluctuated between 0.0025 and 0.0055. The increase of the catalytic activity 



of fresh milk in these tests began at room temperature only after from 24 to 30 



hours, at 37° C. in from 6 to 8 hours, and with iced milk only after from 3 to 



4 days. 



Chloroform did not influence the catalytic activity of fresh or old milk in 

 which the catalase had already developed, but its addition (2:100) prevented 

 the formation of new catalase, and in this way it was possible to determine the 

 catalytic activity of milk as drawn from the animal in barn samples. Formalin, 

 on the other hand, was found to weaken the catalytic process, the reaction being 

 influenced to the greatest extent when the formaldehyde was added to the 

 hydrogen peroxid first. 



Lactic and acetic acid also weakened the catalysis, but with fresh milks the 

 "action is doubled upon neutralization. If alkali is added above the point of 

 neutralization this increase in strength does not occur. On the other hand, milk 

 which has been allowed to become acid or curdled in the incubator, or coagu- 

 lated with lactic acid, does not increase in the amount of activity when neu- 

 tralized. The maximum amount of catalysis was present when milk was 

 allowed to acidify and coagulate at room temperature and after neutraliza- 

 tion. Milk which had been boiled and allowed to curdle gave, as a rule, a 

 higher maximum catalytic activity than raw milks. The catalase seems to be 

 present in the solid particles (precipitate portion) of the serum and in the curd. 

 The multiplication of catalase takes place quicker in the curd than in the serum. 

 From the serum, however, a strong catalytic substance could be isolated. 



Some color reactions for differentiating heated from raw cow's milk, T. 

 Sames (Mdlchw. ZentU., 6 {1910), No. 10, pp. Ji62-Ji68) .— After describing the 

 various color reactions utilized for detecting boiled and raw milk, the author 

 details his findings in regard to the enzymic and nonenzymic characteristics 

 of the supposed ferments of milk. 



With the methylene blue reductase test the author was never able to note a 

 decoloration within i hour, and therefore concluded tliat the view expressed 

 by others that the reductase reaction is probably of bacterial origin and is of no 

 value for differentiating boiled from raw milk is correct. The Schardinger 

 formaldehyde-methylene blue reaction does not depend upon bacterial sources, 

 as was shown in an article previously noted (E. S. R., 23, p. 709). Rendering 

 10 cc. of boiled milk alkaline with 6 drops of normal alkali produces the re- 

 action, and this also renders doubtful the presence of enzyms, as a solution of 

 milk sugar to which 2 drops of an alkaline substance has been added produces 

 the identical reaction. 



In regard to the oxidase reaction the author shows this to be caused by the 

 true protein in an alkaline medium, i. e., by the precipitate obtained with 

 alcohol from serum after the casein has been previously removed with acetic 

 acid. This reaction was still present when the solution was heated to 52° C, 

 but was absent at 60°. 



The author points out that the guaiac and guaiac-hydrogen peroxid method 

 still remains one of the best methods for differentiating raw and boiled milk, 



