186 CHEESE MAKING. 
361. Effect of Fat on Per Cent of Acid in Milk. 
Fat in milk or cream takes the place of some of the milk 
serum. Cream containing 35 per cent fat will curdle with about 
five-tenths of a per cent of lactic acid, and milk containing 5 per 
cent fat will develop hardly more than seven-tenths per cent of 
acid. This is because the fat displaces a portion of the serum. 
362. Abnormal Fermentations. 
When other fermentations than pure lactic acid occur, 
trouble may ensue, for gas may make the curd froth so that it 
may be impossible to use it, or the curd may te slimy or the 
flavor may be impaired. The way out of such a difficulty is to 
use a lactic ferment starter in the milk (112). 
363. Measuring the Acidity. 
As acidity plays such an important part, it may be desirable 
to measure the acid. For this a Farrington alkaline tablet test 
outfit is to be recommended. In addition to the apparatus pre- 
viously described for testing milk for an acidity of two-tenths 
per cent (106), a graduated glass cylinder of 100 ¢. c. capacity 
is required for measuring the water carefully. One tablet is 
used for each 19.5 ¢c. ec. of water, or five tablets for 97 ¢. ¢. of 
water. The titration is then made with 17.5 ¢. ¢. of milk meas- 
ured into the teacup with a Babcock pipette. Each cubic centi- 
meter of the alkali solution required is equal to one-hundredth 
of one per cent of lactic acid. 
364. Moisture, How Regulated. 
A very important: factor in the manufacture of cottage 
cheese is the control of the moisture content. Seventy-five per 
cent of moisture makes a smooth cheese of good texture. More 
water makes it soft and sticky and less makes it harsh like saw- 
dust. The time and temperature used in firming is the impor- 
tant thing here as in the manufacture of Cheddar cheese. The 
following rule will usually apply: Set the milk at 70° F. until 
it coagulates. Cut it fine with a curd knife. Then heat to 90° 
F. in thirty minutes. In ten or fifteen minutes draw the whey 
and dip as described in paragraph 365. 
Van Slyke and Hart made careful investigations with re- 
gard to the influence of the temperature of souring and of sub- 
