378 MANUAL OF MILK PRODUCTS 



Adding the rennet. 



The milk while ripening cools down unless carefully watched. 

 If this has occurred, it must be brought back to the original 

 temperature (85° F.) before adding the rennet. At this tem- 

 perature it has been found necessary to use a curdling time of 

 one and one-half to two hours to secure the texture of the curd 

 desired for Camembert cheese. The amount of rennet required 

 to curdle the milk in this time is calculated by means of the 

 Marschall rennet test or the titration apparatus. 

 Cutting the curd. 



In France the method in general use consists in dipping the 

 curd directly into the forms. Equally good results in most 

 respects, however, have been obtained here with the curd cut. 

 In cutting, the curd knife is passed through the curd in the vat 

 in two directions at right angles, thus producing vertical columns 

 of curd. When the curd has been cut in this way it drains 

 faster, and for that reason a lower degree of acidity is used 

 than with the curd uncut. 



The most satisfactory acidity with cut curd has been found to 

 be from 0.3 to 0.35 per cent. If it is less, the curd is likely to be 

 too soft ; if higher, the curd will drain too rapidly, will become 

 hard and compact, and will not ripen properly. The acidity is 

 tested as follows : a sample of milk is taken with a Babcock 

 pipette holding 17.6 c.c. and is transferred to a glass or beaker. 

 A few drops of phenolphthalein are added and N/10 NaOH is 

 run in from the burette, drop by drop, until a pink color just be- 

 gins to appear. The number of cubic centimeters of soda 

 solution used, divided by 20, gives the percentage of acid in 

 the milk. 



The higher the acidity of the milk, the less rennet it takes. 

 In case the acidity is 0.3 per cent, it will take about 8 to 10 c.c. 

 of the ordinary rennet extract to every 100 lb. of milk to bring 

 the curd to the right consistency in one and one-half to two hours. 

 The necessary amount of rennet is poured into a glass of water 



