DIRECTIONS FOR MAKING THE WISCONSIN CURD 

 TEST 



J. Q. EMERY, Dairy and Food Commissioner, Madison, Wis. 



1. Sterilize milk containers so as to destroy all bacteria in 

 vessels. This step is very important and can be done by heating 

 cans in boiling water or steam for not less than one-half hour. 



2. Place about one pint of milk in covered jar and heat to 

 about 98 degrees F. 



3. Add ten drops of standard rennet extract and mix 

 thoroughly with the milk to quickly coagulate. 



4. After coagulation, cut curd fine with case-knife to facili- 

 tate separation of whey; leave curd in whey one-half hour to 

 an hour; then drain off whey at frequent intervals until curd 

 is well matted. 



5. Incubate curd mass at 98 to 102 degrees F. by immers- 

 ing jar in warm water. Keep jars covered to retain odors. 



6. After 6 to 9 hours incubation, open jar and observe 

 odor; examine curds by cutting the same with sharp knife 

 and observe texture as to presence of pinholes or gas holes. 

 Observe odor 



7. Very bad milks will betray presence of gas-producing 

 bacteria by the spongy texture of the curd and of flavor. 



8. If more than one sample is tested at the same time, dip 

 knife and thermometer in hot water before each time used. 



"Normal milk contains practically no organisms but the 

 straight lactic acid bacteria. These germs produce no gas and 

 no bad odors, but purely lactic acid, and the curd formed 

 therefrom is such as is represented in Figure i. 



"Milk contaminated by the introduction of dust, dirt, fecal 

 matter, or kept in imperfectly cleaned cans, becomes fouled 

 with gas-producing bacteria that break down the milk sugar 

 and so produce gases and usually undesirable odors .... There- 

 fore milks showing the presence of gas or bad odors in any 

 considerable degree are milks 'that have been more or less pol- 

 luted with extraneous organisms or carelessly handled, and as 

 a consequence such milks show a type of curd revealed in 

 Figures 2 and 3." Dr. H. L. Russell. (For further 

 directions, see Farmers' Bulletin, No. 84.) 



