Saccharifying. It is now necessary to saccharify the gelatinized mass. This is accomplished by adding to it a certain amount of malt, whereby maltose or sugar is formed through the action of the diastase. The amount of maltose so created is in proportion to the amount of malt used, the length of time it is acting, the dilution of the mash, and the existence of a proper temperature. The temperature best fitted for this action lies above 122° F., but in order to entirely dissolve the starch a temperature of 145° F. should be used. In addition, at this higher temperature, the bacteria inimical to fermentation are destroyed. A higher temperature than 145° F. should not be allowed, except in extraordinary cases as it injures the effectiveness of the diastase.
Apparatus. The mixture of the malt with the mash may either take place in the heater and cooker itself (see Fig. [2]) or in a preparatory mash vat.
In the first instance, the malt is allowed to enter the cooking cylinder when the temperature of the mash is about 145° F. The mash is stirred until thoroughly mixed when the product is drawn into a receptacle called a drop tub and later reduced to a proper fermenting temperature.
When the Henze type of steamer is used, the pulped mass (see Page 121) is blown into a preparatory mash vat, at the proper temperature. It is left to stand at this temperature for a period varying from twenty minutes to an hour and a half.
Cooling the Mash. Saccharification takes place at a temperature above 122° F., but the proper fermenting temperature is only about 63° F. to 68° F., and hence some means must be adopted for cooling the hot mash to this temperature and for so cooling it in a relatively short time.
Fig. 3.—Mash Cooler, Air System.
Cooling may be accomplished by submitting the mash to currents of air; to contact with cold water coils or by the use of ice. One of the simplest coolers of the first class is shown in Fig. [3].
This consists of a shallow panlike tank A having means for introducing and drawing off the mash. Rotating in the center of the tank is a vertical shaft C carrying radiating stirrer arms B. Braces M extend to the middle of these arms and the arms carry a number of blades or paddles b, which extend down into the mash. Above the arms, mounted loosely on the same shaft, but rotating in the opposite direction, are fans H supported by arms J which create air currents over the agitated mash. These fans move at a much faster rate than the stirrers B.