368 SCIENCE AND PRACTICE OF CHEESE-MAKING 



of using larger amounts of rennet-extract. Increased 

 amounts of whey in cheese may, if not too excessive, 

 favor more rapid action of the peptic ferment in 

 rennet, because increase of whey in cheese means 

 increase of milk-sugar and this means more lactic 

 acid. 



(7) Commercial pepsin, when used in milk and 

 cheese, behaves in a manner closely resembling 

 rennet-extract; since it acts only in the presence of 

 some a'cid or acid salt and forms relatively small 

 amounts of amino acids as compared with caseoses 

 and peptoojes. 



(8) Rennet-extract, therefore, contains an enzym 

 which has the power of performing the same kind and 

 amount of digesting work in cheese-ripening as pepsin. 



(9) Rennet-extract appears to contain, in addi- 

 tion to the peptic ferment, another ferment which 

 has the power to digest milk-casein to some extent in 

 the absence of acids or acid salts. 



ACTION OF GALACTASE IN CHEESE- 

 RIPENING 



The main characteristics of the milk-enzym, galac- 

 tase, have been discussed already (p. 297). It has 

 been shown that galactase prepared from separator- 

 slime in the manner described by Babcock and Rus- 

 sell contains, at least, two other enzyms. But we are 

 not particularly interested to know in this discussion 

 whether galactase is one or two or more enzyms ; 

 the point of importance here is that milk contains a 

 substance which has the power under certain condi- 

 tions of converting milk-casein and the paracasein 

 of cheese-curd into soluble forms of proteins and 



