Fermentations in Milk. 



77 



jar from each sample of milk. These tests may be made 

 in any receptacle that has been cleaned in boiling water, 

 and to keep the temperature more nearly uniform these 

 jars should be immersed in warm water, as in a wash tub 

 or some other receptacle. When the milk is about 95 F., 

 about ten drops of rennet extract are added to each sample 

 and mixed thoroughly with the milk. The jars should 

 then remain undisturbed until the milk is completely 

 curdled; then the curd is cut into small pieces with a case 

 knife and stirred to expel the whey. The whey should be 

 poured off at frequent intervals until the curd mats. If 

 the sample be kept at blood heat (98 F.) for six to eight 

 hours, it will be ready to examine. 



FIG. 18. Improved bottles for making curd test. A, test bottle complete; B, 

 bottle showing construction of cover; S, sieve to hold back the curd when bottle 

 is inverted; C, outer cover with (D IT) drain holes to permit of removal of whey. 



More convenient types of this test than the improvised 

 apparatus just alluded to have been devised by different 

 dairy manufacturers. Generally, they consist of a special 

 bottle having a full-sized top, thus permitting the easy 



