CHAPTER III 

 COAGULATING MATERIALS 



AT the present time, two substances are used to coag- 

 ulate milk for cheese-making, rennet extract and com- 

 mercial pepsin. 1 Many substances will coagulate milk, 

 such as acids and other chemicals. Enzymes in certain 

 plants will also coagulate it. 



The curing or ripening of the cheese seems to depend 

 on the physical and chemical properties of the curd, on 

 the activity of certain organisms and on enzymes pro- 

 duced by them or in the milk. Rennet extract and 

 pepsin are the only known substances which will produce 

 curd of such character as will permit the desired ripening 

 changes to take place. Until recently, rennet extract 

 was principally used to coagulate the milk, but because 

 of the scarcity, pepsin is now being substituted. 



44. Ferments. Many of the common changes tak- 

 ing place in milk are due to fermentations. The souring 

 of milk is one of the most familiar cases of fermentation. 



1 Stevenson, C., Pepsin in cheesemaking, Jour. Agr. (New 

 Zeal.) 14 (1917), pages 32-34. 



Todd, A., and E. C. V. Cornish, Experiments in the prepara- 

 tion of homemade rennet, Jour. Bd. Agr. (London) 23 (1916), 

 no. 6, pages 549-555. 



Besana, C., Lack of coagulating ferment in cheesemaking, 

 Staz. Sper. Agr. Ital. 49 (1916), pages 10-12. 



Van Dam, W., Rennet economy and substitutes, Verslag. 

 Ver. Exploit. Proefzuivelboerderij. Hoorn, 1914, pages 45-46. 



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