Treating the Grain.—Malt is produced by soaking barley or other grains in water and spreading in thin layers on the floors of the malting rooms. Being moist and in consequence supplied with artificial heat, the grains begin to sprout. As the rootlets grow in size a product is being formed in the germ that has the power to convert starch into sugar. This product is called Diastase. This reaction is still clouded with a good deal of mystery, and it has as yet never been clearly defined.
We know this much, however, that some parts of the nitrogenous matter of grains are chemically changed into Diastase.
Practice teaches the maltster, by the size the rootlets attain, when the maximum diastasic strength of the malt has been reached.
The sprouting of the malt is now arrested by drying the malt in kilns at a temperature of 131 to 176 degrees F., which evaporates the moisture and kills further germination.
For malting purposes barley is mostly used, as its diastasic strength exceeds that of any other grain.
The Yeast Mash.—For preparing the yeast mash crushed malt and rye is employed, although other grains are used to replace part of the rye, such as corn and buckwheat.
Experience teaches, however, that the best results are obtained by the use of barley malt and rye only.
The materials are selected with great care. The water employed is boiled, the rye must be clean and free from dust, and the malt free from mould. The rye is first soaked in water and then crushed.