542 Circular No. 7. 



(milk, whey, cream or starter) which you wish to test, and place it in the 

 white cup. Add two drops of the phenolphthalein indicator. Then allow 

 the alkaline solution to run into the cup from the burette, one drop at 

 a time, until the fluid in the cup, which is being constantly stirred, shows 

 a very faint pink color. By reading the graduations on the burette we 

 can ascertain the amount of acid in the substance tested. Each i/io 

 cubic centimeter of alkali represents i/ioo per cent, of acid in the fluid. 



AMOUNT OF ACID TO BE DEVELOPED AT EACH STAGE 



In cheese-making. — The amount of lactic acid developed depends 

 largely on the condition of the curd and no fixed amount can be accepted 

 as a set rule. Other conditions equal, the acidity should be uniform from 

 day to day. 



The proper firming of the curd in the whey before too much acid has 

 been formed is the secret of cheddar cheese-making, and with this fact 

 in mind, the following directions should give accurate results : 



Export cheese Home-trade cheese 



.20 to .21;^ before adding rennett .18 to .20^ 



.14 to .145^ before heating curd .13 to .14^ 



.16 to .18;^ before removing whey .15 to .17^ 



.24 to .30,'^ when all whey is removed 



and curd is packed .23 to .26,^ 



.65 to .75^ before milling .60 to .65^ 



.yo to .110^ before salting .65 to .90^ 



.70 to .80^ in starter .70 to .80;^ 



In butter-making. — The amount of acid should vary with the amount 

 of butter-fat in the cream. 



Per cent, fat Per cent, acid 



20 ^2 



30 63 



40 54 



50 45 



In commercial starter , 70 to .80 



