New York Agricultural Experiment Station. 



77 



Table V. — Effect of Acin CoiMpounds Upon the Digestive Action of the 



Rennet. 



From the above results it is clearly seen that in the presence of 

 the salt-soluble compound the rennet enzyme was able to 

 change considerable quantities of nitrogen into a water-soluble 

 form while under similar conditions except for the action of the 

 acid the rennet enzyme did very little work. From this we con- 

 clude that the activity of the lactic-acid bacteria in changing 

 sugar into acid is a necessary preliminary to the digestive action 

 of the rennet in cheese under normal conditions. 



CONCLUSION. 



In the preceding pages the attempt has been made to follow the 

 process of cheese-making and the first steps of cheese-ripening 

 and to trace in outline the part played by the acid - forming 

 bacteria. It has been shown that all of the observed changes up 

 to the point where the digestion by the rennet leaves ofif are either 

 the direct result of the action of these bacteria or are largely in- 

 fluenced by bacterial action. 



A discussion of the early stages of cheese-ripening would be 

 incomplete unless consideration was given to the part played by 

 the enzymes of the milk itself. However, the efifect of these en- 

 zymes is not confined to the first stages of the ripening, and as the 

 subject will be later treated in a separate bulletin it will not be 

 further discussed at this time. 



Under the conditions which exist in normal cheddar cheese the 

 action of the rennet enzymes probably extends but little beyond 



