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 
cams 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 warrmwater. 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 1. 
“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.) 
