RENNET AND RENNETING. 159 



Rennet in powder form is much more concentrated, 

 is less likely to be adulterated, and if kept dry is in 

 less danger of spoiling as compared with the liquid 

 form. It would also reduce the cost of transportation 

 and expense of bottling or putting in casks, yet it does 

 not seem to meet with favor. The rennet powder 

 should be grayish white in color, with little smell, 

 and be easily dissolved in water. We expect to see 

 this form of rennet come into more general use in 

 the near future. 



The action of a weak acid is apparently similar to 

 that of rennet, but there is a marked difference. The 

 acid causes coagulation by neutralizing the lime salts, 

 which cause the casein to be held in solution. The 

 rennet acts on the casein of milk, splitting it into 

 two parts a soluble which passes off in the whey 

 and is lost for cheesemaking, and an insoluble which 

 forms a chief part of what is known as curd. How- 

 ever, the action of rennet is not as yet fully under- 

 stood. By some it is considered that rennet acts by 

 katalysis or contact, causing the coagulation of the 

 casein by its presence. This view is not accepted 

 very widely. We know it is a powerful agent, but as 

 to the exact nature of its method of producing coagu- 

 lation we are yet largely in the dark. It does not act 

 on milk if it has been boiled, or if an alkali be 

 present. Large quantities of water in milk also 

 retard rennet action. In hot weather, when patrons 

 use soda in the milk to keep it sweet, the cheesemaker 

 has trouble in securing a proper coagulation. This 

 is also true on wet mornings when considerable rain- 

 water gets into the milk. 



