When the milk has been tested and accepted it should be strained through several thicknesses of clean cloth into the ripening machine, bringing the temperature in the different vats to the same point, so that as the milk is used it will all be in the same condition. In cold weather the temperature should be held at 70° F., while during the warmer seasons from 60° to 65° is desirable. In cloudy, murky summer weather a lower temperature will be required. Under such conditions the temperature should be held at from 55° to 60° F. until the storm is passed, when it should again be held at the normal temperature named.
Reasons for Culture.
—To make an acidity test, a 20 cc. pipette is used for measuring the milk or cream. Each cubic centimeter of solution is equal to two one-hundredths of one per cent acid, hence if 10 cc. of solution is necessary to turn the milk or cream a pink color, the milk would contain just two-tenths of one per cent acid and would be sweet. Any more than that would show the milk too sour for use. In receiving sweet milk, it must be assumed to contain impure bacteria, which only await the proper temperature to develop and sour the milk, producing bad flavors. It must be neutralized by pasteurizing and then cultivated with pure bacteria.
Another advantage obtained in the use of the “starter” is, that it permits the ripening of milk and cream at low temperatures. Bacteriologists state, and it is proved by experience, that a temperature of about 65° F. is most favorable to the development of the best fermentation in ripening milk and cream. Prior to the use of cultures it was customary to sour the milk at a much higher temperature, which was correspondingly favorable to all the objectionable bacteria in the milk. Without the use of the “starter” the conditions were beyond the control of the operator.
Cream Ripeners.
—To produce these conditions the milk should be pasteurized, which can be performed by the use of a standard pasteurizer of the type shown in [Fig. 164]. There are a variety of pasteurizers in use.
This apparatus is equipped with an internal revolving coil of pipe or discs, built sufficiently strong to withstand the pressure of steam, water or brine circulated through the coils or discs, which is usually done in the order named.
To pasteurize, the milk is heated to a temperature of 180° F. for twenty minutes. This practically destroys the bacteria present. The milk is then rapidly cooled by passing cold water or chilled brine, or both, in turn, through the coil to reduce the temperature of the body quickly to that desired, usually 55° to 70° F., according to conditions as described. The starter or culture is introduced and the milk agitated to insure a thorough intermingling.
FIG. 164.—WIZARD PASTEURIZER AND RIPENER, STYLE B WITH VITRIFIED PORCELAIN ENAMELED JACKET AND “SIDE LIFT” PIANO HINGE METAL COVER.