tances. As the process of hydrolysis proceeds, the amyloins become
gradually poorer in amylin and relatively richer in maltose-groups. The
final products of transformation, according to Brown and J.H. Millar, are
maltose and glucose, which latter is derived from the hydrolysis of the
stable dextrin. This theory may be applied in practical brewing in the
following manner. If it is desired to obtain a beer of a stable
character--that is to say, one containing a considerable proportion of
high-type amyloins--it is necessary to restrict the action of the diastase
in the mash-tun accordingly. On the other hand, for mild running ales,
which are to "condition" rapidly, it is necessary to provide for the
presence of sufficient maltodextrin of a low type. Investigation has shown
that the type of maltodextrin can be regulated, not only in the mash-tun
but also on the malt-kiln. A higher type is obtained by low kiln and high
mashing temperatures than by high kiln and low mashing heats, and it is
possible therefore to regulate, on scientific lines, not only the quality
but also the type of amyloins which are suitable for a particular beer.

The chemistry of the nitrogenous constituents of malt is equally important
with that of starch and its transformations. Without nitrogenous compounds
of the proper type, vigorous fermentations are not possible. It may be
remembered that yeast assimilates nitrogenous compounds in some of their
simpler forms--amides and the like. One of the aims of the maltster is,
therefore, to break down the protein substances present in barley to such a
degree that the wort has a maximum nutritive value for the yeast. Further,
it is necessary for the production of stable beer to eliminate a large
proportion of nitrogenous matter, and this is only done by the yeast when
the proteins are degraded. There is also some evidence that the presence of
albumoses assists in producing the foaming properties of beer. It has now
been established definitely, by the work of A. Fernbach, W. Windisch,
F.Weiss and P. Schidrowitz, that finished malt contains at least two
proteolytic enzymes (a peptic and a pancreatic enzyme).

[Illustration: BREWING

PLATE I.

FIG. 5.--REFRIGERATORS IN "LAGER" BREWERY OF MESSRS. ALLSOPP.

The hot wort trickles over the outside of the series of pipes, and is
cooled by the cold water which circulates in them. From the shallow
collecting trays the cooled wort is conducted to the fermenting backs.