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, 



