MILK 413 
This process is known as pasteurization. A few of the 
larger cities now require all ordinary milk to be pasteur- 
ized before it is permitted to be sold. Several forms of 
apparatus have been devised for this purpose, some of 
which are expensive and complicated and others very 
simple. After milk has been properly heated, for best 
results it should be quickly cooled and held at a tempera- 
ture of 50 degrees or less until it is consumed. 
7. Cooling.—The cooling of milk is 
for the purpose of checking and lessen- 
ing the growth and multiplication of the , 
lactic germs that sour the milk. When @ 
milk is warm it is in the condition that 
most satisfies these tiny creatures. They CP°W™# oF Bacteria 
are less active in milk cooled down to a of hecteda a Sat 
low temperature, and in frozen milk fs 29 perares our: 
they are content to sleep and rest and pepresentin® |* sing’s 
wait for better fortune. On farms where §°81°So degrees 306 
market milk is produced the custom is °**t*!* 
to cool the milk with ice immediately after milking. Even 
though the greatest care is exercised in handling milk, 
unless cooled to a low temperature, the milk will not 
keep sweet longer than a day or two. 
8. Cream.—The lighter portion of milk, or that which 
rises to the surface when the milk is allowed to stand, 
or which can be otherwise separated by centrifugal force 
from untreated milk, is the product known as cream. It 
contains a much higher percentage of fat than milk, the 
other constituents being correspondingly lower, due to 
removal of water. In cream the fat globules are in sus- 
pension as in milk. The methods in use to obtain cream 
are shallow pans, deep setting, and centrifugal force or 
cream separators. Cream may be thick or thin, or any 
degree between the two extremes. An average cream 
