SO-CALLED 'BIOLOGICAL PROPERTIES' OF MILK 97 



Variations in Catalase Content. The content of catalase is greatly 

 increased in inflammatory conditions of the udder, and Kooper (3) 

 believes that differences may be detected between the breed of cows 

 and the catalase content of milk. There is, further, a general con- 

 sensus of evidence to show that the catalase content of milk 

 increases when the gland is nearly 'dry/ and also probably in 

 colostrum. It appears, therefore, that when the gland is com- 

 mencing or ceasing its activity, or when there is inflammation, 

 the amount of catalase is usually increased. 



In view of the very large amount of catalase present in blood, 

 it is unlikely that no trace of this enzyme would be found in the 

 milk, more especially when the blood supplied to the gland is 

 probably increased or when the milk supply is running short. 

 For further detailed information upon this subject compare the 

 work of Bier, Giffhorn, Gerber and Ottiker, Spindler, Koning, 

 and Bertin-Sans and Ganjoux (i). 



On the Presence of Amylase. The action of amylase is to 

 break down starch or amylum into simpler substances. It appears 

 that starch is not converted by this enzyme to a further stage 

 than maltose, and that unless this medium be acid (Mellanby and 

 Woolley) it remains for the most part in the stage of dextrins. 



Amylase has been shown to be present in milk, and it is probable 

 that in this medium starch is not split further than dextrin. The 

 difficulties, however, of estimating the end point of this reaction 

 in milk are very great, since it is almost impossible to detect the 

 formation of minute quantities of maltose. 



Amylase in Cows' Milk. Investigators are not unanimous 

 upon the presence of amylase in cows' milk, and it does not appear 

 that it is present in more than very small quantities in the milk 

 of this species. 



Spolverini (1902) was unable to obtain evidence of the presence 

 of amylase in cows' milk, but Zaitschek (1904) found evidence of 

 amylolytic activity in all the samples of milk examined by him. 

 He estimated the amount of starch hydrolysed by weighing the 

 increase of reducing sugar which occurred during incubation, the 

 sugar being calculated as maltose. 



Koning (1906) showed that certain bacteria were capable of 

 producing amylase, but he believed that the action found by him 

 in cows' milk was not due to bacterial contamination. He collected 

 the milk with the greatest care and the investigations were carried 

 out over short periods only. He found that about -015 to -02 gm. 

 of starch was decomposed by 100 c.c. of milk in half an hour. The 

 first and middle milks were richer in amylase than the strippings, 

 but any increase in strength beyond that given was regarded by 

 him as pathological. The activity was destroyed by heating the 

 milk for forty-five minutes at 68 C. 



Giffhorn found that 100 c.c. of milk would decompose from *oi 

 to -25 gm. of starch, the amount of enzyme present being increased 



