34 A Nezv Dairy Industry. 



•different from other forms of curdling of milk, which 

 are partially based — similar to the acid curdling — on 

 the action of a living ferment, the bacteria ; partially, 

 however, their appearance is due to the action of a 

 dead or so called chemical ferment. 



The best known curdling is the one accomplished 

 by rennet which is a chemical ferment. By this pro- 

 cess the casein of the milk is chemically changed, 

 inasmuch as it is transformed after separating the 

 "whey protein," a peptonic matter, into so-called cheese 

 or, as we often call this albuminous matter, into para- 

 casein. 



This rennet curdling is similiar to another curdling 

 of milk, which must be laid to the action of certain 

 bacteria and which envolves a simultaneous transfor- 

 mation of the casein. Certain bacteria are able to 

 cause a ferment to exude, which acts similarly to 

 rennet on milk, forcing it, without previous acidulat- 

 ing to a rennet-like coagulation ; however, in most 

 cases this " bacterial rennet," as we might call it, 

 seems to have the effect of again dissolving the 

 formed cheesy mass and transforming it into a soluble 

 matter — " peptonising the albumen," as the scientist 

 would call it. This bacterial ferment, therefore, be- 

 haves quite differently from the rennet ferment which 

 does not have the dissolving power. It is, however, 

 not excluded that these bacteria may, at the same 

 time or later, separate a second ferment which posesses 

 this very effect to a certain degree. 



Now, raw milk at all times contains such bacteria 



