CHAPTER XX. 
COTTAGE, NEUFCHATEL AND SOFT CREAM CHEESE. 
358. Utilization of Skim Milk. 
A great many city dairies that turn a large part of their 
milk into cream have skim milk left on their hands, and to 
make the business pay as well as possible, they naturally look 
for a means of disposing of this skim milk. Usually there is 
quite a demand for the sour-milk curd, known as Dutch cheese, 
cottage cheese, or Schmterkase. 
359. Method of Manufacture. 
As this has been made probably for centuries, it would 
seem an easy task, and so it is, if conditions are just right, but 
as large dairies sometimes have difficulty in obtaining uniform 
results, a short chapter treating about the manufacture of this 
cheese from a scientific standpoint may be helpful. 
360. Curdling Power of Acid. 
As has been explained the casein of milk is precipitated by 
rennet and dilute acids. Sweet milk can be heated to the boil- 
ing point without curdling, but as acid develops, the milk will 
first be coagulated at the higher temperatures, and then as the 
acidity increases, the temperature at which it will curdle is 
gradually lowered until skim milk containing .f to .7 per cent 
of acid will curdle spontaneously. At about 70° F. skim milk 
will not increase in acidity above nine-tenths of a per cent, as 
the growth of the lactic acid germ is checked. Van Slyke and 
Hart found approximately 5 per cent of sugar in milk used by 
them. When the milk contained .9 per cent acid (the maximum 
amount), 1.5 per cent milk sugar, or 28 per cent of that orig- 
inally present, has disappeared; 62 per cent of the milk sugar 
that disappeared was left in the form of lactic acid. The re- 
mainder probably disappeared in the form of carbonic acid and 
other volatile sutstances. 
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