572 USE OF THE CURD FOUND IN THE CALF's S\ JMACE 



Using the same skin a second lime. — If this then be a true explanation 

 of the action of rennet — if the coajijulating ingredient in it be merely a 

 portion of the changed niembianoof the stomach itself — it is obvious that 

 the bag, after being once used, may be again salted and dried with ad- 

 vantage. The slow decay may, after a second salting, become still 

 slower, and thus it may require to be longer kept after the second than 

 after the first salting, before it will give a rennet as poweriul as that 

 which was first extracted from it. But txuless it be merely the inner 

 membrane of the stomach and intestines which is capable of undergoing 

 that, kind of change upon which the coagulating power depends, there is 

 no apparent reason, as I have already sta*ed to you, why the same 

 maiv- skin may not be salted, dried, and steeped many times over. 



Use of whey. — Again, in the making of rennet there seems some pro- 

 priety ui the use of whey rather than of water. The whey may contain 

 a portion of the rennet which had been adJed to the milk from which 

 it was extracted, and may thus be able of itself to curdle milk. It is 

 sure also to contain some milli-sugar, which, being changed into acid 

 when the whey is poured upon the dried stomach, will add to the coag- 

 ulating power of the rennet obtained. 



Use of the curdled milk contained in the stomach. — Docs the view we 

 have taken of the action of rennet throw any light upon the use of the 

 curdled milk fijund in the stomach ? Is it of any service, or ought it to 

 be rejected? 



We are certain that it must be of service m coagulating milk, since in 

 Cheshire, according to Dr. Holland, it is frequently taken out and salted 

 by itself for immediate use. But a slight consideration of the properties 

 of casein, as I have already stated them to you (p. 562), will explain 

 why this curdy matter should be serviceable for such a purpose. 



You will recollect that casein, after being exposed to the air for a short 

 time, acquires, like animal membranes, the property of converting sugar 

 into lactic acid (p. 562), and of curdling milk. Now the curdy matter 

 taken from the stomach of the calf, after being exposed to the air, ac- 

 quires this property as completely as a more pure curd will do. If salted 

 and kept, it will be changed still further, and will acquire this property 

 in a greater degree. In short, keeping will affect the curd precisely in 

 the same way as it does the membrane of the stomach itself, and will 

 render it alike fit to be employed in the preparation of rennet. Nor is 

 it unlikely that fresh well-s(pieezed curd, if mixed with much salt and 

 kept in slightly covered jars for 10 or 12 months, might yield a rennet 

 possessed of good coagulating properties. 



It thus appears that, so far as economy is concerned, the curdy matter 

 contained in the calfs stomach ought to be preserved and salted for use. 

 If in any district this curd be suspected to impart an unpleasant flavour 

 to the cheese, this bad effect may probably be remedied by taking it out 

 of the stomach, washing it well with water — as is done in some dairy 

 districts — mixing it with salt, and then returning it into the stomach 

 again. 



Another practical conclusion may also be drawn from this explanation 

 of the action of the stomach. Since it is the membrane alone that acts, 

 there can no loss accrue by carefully washing the stomach as well as 

 the curd it contains. On the contrary, by so doing we may remov« 



