298 SCIENCE AND PRACTICE OF CHEESE-MAKING 



to change insoluble proteins like milk-casein into 

 soluble forms. 



The following have been given as some of the more 

 prominent characteristics of galactase. ( i ) Galac- 

 tase readily attaches itself to finely divided particles 

 in suspension like milk-casein and fat-globules ; hence, 

 it is found in separator-slime and in cream to a greater 

 extent than in milk or skim-milk. (2) The most 

 favorable temperature for the action of galactase lies 

 between 98 and 108 F. Heated for ten minutes 

 above 168 F., its activity is destroyed, as shown by 

 the following table : 



EFFECT OF HEAT ON GALACTASE IN MILK 



(3) Free acids, especially hydrochloric acid, retard 

 the activity of galactase. Neutral or alkaline reac- 

 tions favor its action. (4) Many disinfectants, like 

 mercuric chlorid, carbolic acid, formaldehyd, carbon 

 disulphid, etc., retard or prevent the action of galac- 

 tase. (5) Its activity is greater in the early stage 

 of working, as measured by the rapidity with which 

 casein is changed into soluble compounds. 



As a result of their work, Babcock and Russell 

 concluded that galactase is a trypsin-like ferment, 



