REPORT OF THE DEPARTMENT OF 

 BACTERIOLOGY. 



THE ROLE OF THE LACTIC-ACID BACTERIA 



IN THE MANUFACTURE AND IN THE 



EARLY STAGES OF RIPENING OF 



CHEDDAR CHEESE.* 



H. A. HARDING. 



SUMMARY. 



1. Lactic-acid bacteria are always present in factory milk. 



2. These lactic-acid bacteria check the growth of other forms by 

 breaking up the sugar into acid and finally make up more than ninety 

 per ct. of the total number of germs present in the milk and cheese. 



3. The acid formed by these bacteria hastens the curdling action 

 of the rennet. 



4. This acid combines with paracasein to form at least two different 

 compounds — paracasein monolactate and paracasein dilactate. The 

 paracasein monolactate is normally formed in large quantities. 



5. This formation of acid is necessary to the activity of the rennet 

 pepsin. 



*A reprint of Bulletin No. 237. 



