/ FIG. 1.--_H. hexastichum._
| a. Three spikelets _in situ_ on the rachis, showing short
| internodes.
| b. Spike. Median spikelets uppermost, and with lower awns
| removed.
Six-rowed< c. Spike. Lateral spikelets uppermost, and with lower awns
barleys. | removed.
| FIG. 2.--_H. vulgare._
| a. Three spikelets _in situ_ on the rachis, showing long
| internodes.
| b. Spike. Median spikelets uppermost.
\ c. Spike. Lateral spikelets uppermost.
/ FIG. 3.--_H. zeocriton._
| a, d. Spikelets. Rachis edgewise, showing short internodes.
| b. Var. _zeocrithum_ (fan barley). Spike converging.
Two-rowed< c. Var. _erectum_ (Goldthorpe). Spike parallel.
barleys. | FIG. 4.--_H. distichum._
| a. d. Spikelets. Rachis edgewise, showing long internodes.
| b. Var. _nutans_ (Chevallier).
\ c. Ouchak barley.
Figures 1-4 redrawn from a paper by E. S. Beaven in _Journ. Fed. Inst.
Brewing_ (1902), 8. 542.]
In an ear of barley the primary axis or rachis is divided into
internodes of which there may be any number up to forty. Each internode
bears three single-flowered spikelets arranged alternately on either
side of the rachis. In the six-rowed varieties the whole of these
spikelets attain maturity, whilst in the two-rowed varieties only one on
each side of the rachis, viz. the median, develops. British beer is
brewed principally from the malt made from home-grown two-rowed barleys.
Of late years, however, it has been found advantageous to employ a
proportion of malt made from the thinner and more husky foreign barleys,
mostly six-rowed varieties. The corns of two-rowed barleys are as a rule
plumper than those of six-rowed barleys.
The most favourite barley for malting purposes grown in the United
Kingdom is the narrow-eared two-rowed _H. distichum_, commonly known
as Chevallier, from the name of the original cultivator, the Rev. John
Chevallier. Of late years the quantity of barley of the so-called
Goldthorpe type (_H. zeocriton_), used for malting, has increased. The
paleae or outer coverings of the corns of this variety are somewhat
"greasy" in appearance, and do not adhere so closely to the corn as in
the Chevallier. The corns of Goldthorpe barley possess a small dimple
or transverse furrow near the basal end. Further the basal bristle or
rachilla (the prolongation of the axis or point from which the corn
was originally developed) is invariably covered with long hairs,
whilst in the case of Chevallier it has generally very short hairs. In
the variety of Chevallier known as Archer, however, the rachilla has
somewhat long hairs. Further the corns of Chevallier barley lie nearly
vertical, that is almost parallel to the rachis, whereas in Goldthorpe
they are spread out at a greater angle, hence the name fan or peacock
barley given to that variety commonly known as sprat. It is believed
by some brewers that Goldthorpe barleys never yield malt of so high a
quality as do Chevallier barleys. On the other hand, when well
matured, Goldthorpes work evenly and freely on the malting floors; and
from an agricultural point of view they have the advantage of standing
up better against unfavourable weather conditions on account of their
stouter straws. Numerous fresh varieties of barley are continually
being introduced as a result of artificial cross-fertilization, but
cross-fertilization rarely if ever occurs naturally.
Hungarian two-rowed barleys are excellent as regards quality, and
command a high price. The so-called Californian Chevallier and Chilean
Chevallier contain a certain admixture of the six-rowed _H. vulgare_.
Of the imported thin barleys may be mentioned Brewing Californian,
Brewing Chilean, Danubian and Smyrna (Yerli), all for the most part
six-rowed varieties; also Ouchak, consisting principally of a
two-rowed variety. For the manufacture of grain spirit a malt of high
diastatic activity is required, and this is largely made from a very
thin barley shipped from Odessa.
In the common six-rowed English barley or Scottish bere (_H.
vulgare_), the two lateral rows of spikelets springing from one side
of the rachis, either partially or entirely intersect and overlap the
alternate lateral spikelets which spring from the opposite side of the
rachis. This has given rise to the term "four-rowed barley." Figs. 1-4
show some typical barleys in the ear.
The production of new varieties by cross-fertilization has of late
years attained a degree of almost mathematical precision by the
application of the law of inheritance first discovered by Gregor
Mendel in 1865, and brought to light in 1901 independently by de
Vries, Correns and Tschermak.
_Constitution of Barley._--A grain of barley is shuttle-shaped; the end
containing the germ which was originally attached to the rachis is known
as the proximal end, whilst the opposite end of the corn is called the
distal end. A deep furrow runs down the more convex side, which is
accordingly denoted the ventral side, the opposite side being
distinguished as the dorsal side. Within the ventral furrow at the
proximal end is the rachilla already referred to. The skin or husk of a
barleycorn consists of two paleae, one adhering to the dorsal side (the
palea inferior) and the other to the ventral side (the palea superior);
the former overlaps the edges of the latter. The awn or beard is merely
an elongation of the palea inferior. If the two paleae are removed from
a barleycorn after soaking it in water, it will be seen that there are
other skins completely enveloping the embryo and endosperm. These are
the true skins, and are known as the pericarp and the testa
respectively. It may here be mentioned that A. J. Brown has shown
recently that the embryo and endosperm of a barleycorn are enclosed in a
semi-permeable membrane, i.e. one which allows the passage of water to
the interior of the corn, but not of certain salts and acids. This
property appears to be associated with one of the layers of the testa.
Next to these skins will be seen the triple layer of thick-walled
square-shaped aleurone cells.
The histology of the barleycorn is best studied by the examination of
sections under the microscope. The grain consists of two main portions,
the embryo or germ, and the endosperm, the storehouse of reserve
materials for the growing plant.
The accompanying illustrations show portions of longitudinal sections
of a barleycorn magnified to different degrees.
On examining fig. 5, which represents a section of the germ end of a
grain of barley cut through the ventral furrow, it will be noticed
that the rudimentary leaves, stem and roots are distinguishable. The
embryo lies embedded in a mass of cells, the part dividing it from the
endosperm being known as the scutellum. Special note should be taken
of the elongated cells known as the absorptive epithelial layer, which
has certain very important functions to fulfil during the process of
germination, notably in feeding the embryo when it begins to develop
into a young plant. Next to this, actually between the scutellum and
the endosperm, will be seen a layer of empty cells. These at one time
in the history and the development of the corn contained starch
granules, but this starch was absorbed during its later development by
the embryo. It will be observed further that the endosperm is filled
with a network of thin-walled cells closely packed with starch
granules, and smaller granules of proteïn matter (fig. 6). Nearest the
skin will be seen the triple layer of aleurone cells already referred
to (fig. 7).
[Illustration: FIG. 5.--Median longitudinal section of a barleycorn
showing the germ and its appendages.
a, Rudimentary leaves or plumules;
b, Rudimentary stem;
c, Rudimentary root;
d, Empty starch cells of the endosperm;
e, Absorptive epithelial layer;
f, Compressed layer of empty cells;
g, Starch cells (filled).]
[Illustration: FIG. 6.--Section showing absorptive epithelial layer more
highly magnified.
d, Walls of starch cells;
e, Epithelial layer;
f, Compressed layer of empty cells;
g, Cells filled with starch granules;
h, Cells of the scutellum.]
_Germination._--The barleycorn in its resting stage is in a state which
may be described as one of dormant vitality; it respires very slowly
and thus loses weight during storage. The best and driest barleys are
said to lose 1.3% of their weight in the first year, 0.9% in the second,
and 0.5% in the third. The loss is considerably more with coarse and
damp samples. When the grain is steeped this dormant vitality gives
place to that complicated series of processes comprised under the
general term germination. When germination begins, enzymes are secreted,
and these act on the reserve materials, starch and proteïns of the
endosperm, converting them into simpler compounds, capable of diffusing
to various parts of the growing germ. Following this, starch and
proteïns are re-formed, the former being deposited in the tissues of the
germ and in the cells of the scutellum, which previously were almost
free from starch; the proteïn matter deposited in the latter disappears
to a considerable extent, and the protoplasmic content of the cells
assumes a very granular appearance. The pointed mass of cells
constituting the root-sheath is pushed forward by the root which
protrudes through the base of the grain. It is at this stage that the
barley is said by the maltster to "chit." After the first rootlet has
broken through the ends of the sheath, it is followed by others. The
cotyledonary sheath begins to elongate on the third or fourth day of
germination and ruptures the true covering of the seed; it then grows
upwards between this and the husk and forms the acrospire or "spire" of
the maltster.
[Illustration: FIG. 7.--Section showing the aleurone layer.
g, Starch cells;
i, Aleurone layer;
k, Layers which collectively constitute the husk.
[Figs. 5-7 from Sykes & Ling, _Principles and Practice of Brewing_
(1907), Charles Griffin & Co., Ltd.]]
According to Brown and Morris, when the first rootlet is breaking
through the sheath, starch begins to appear in the tissues of the
grain, also in the protoplasm of those cells which are nearest the
epithelial layer, and it gradually invades the deeper-seated cells.
Further the cellulose walls of the endosperm, situated immediately
above the secretory layer, are partially dissolved, the dissolved
matter passing into the scutellum, there to be transformed into
starch. Brown and Morris state that this process gradually extends to
the cellulose walls of the endosperm, and until these are affected
there is no evidence of any solvent action on the starch granules
themselves. Thus according to these authors the first enzyme to be
formed is one which dissolves cell walls, and it was consequently
termed by them a "cytohydrolyst." They assert further that the
so-called mealy or modified condition, which the maltster desires to
bring about to the fullest degree, depends on the extent to which the
cell walls have been affected, and they enter into a minute
description of the entire disappearance of these during the malting
process. On the other hand, J. Grüss has pointed out that the action
which takes place on the cell walls of the endosperm during
germination does not consist in their complete solution. Schulze has
shown that these cell walls consist of two carbohydrates, an araban
and a xylan. Grüss states that the araban is completely dissolved,
whilst the xylan is more or less unattacked. The cell walls become,
however, transparent so that they can only be seen in sections which
have been stained; Brown and Morris examined unstained sections. The
writer (A. R. Ling) has proved that the cell wall is present in the
most friable and well modified finished malt.
_Condition._--Barley is bought in the open market solely on the evidence
of certain external signs, and judgment can only be acquired by long
experience. The corns should be plump, even in size, and the colour
should be uniform from end to end. The sample should have a sweet
odour, and it should be dry to the touch. The presence of light or
weevilled corns may be detected by the fact that they float in water.
Careless threshing or dressing is responsible for much damage done to
barley. In this way many of the corns may be broken, have the palcae
partly stripped off or portions removed along with the awn. All broken
and dead corns are prone to become mouldy on the malting floors, the
contagion thus presented becoming general. E. R. Moritz drew attention
in 1895 to the ill effects of close dressing, and more recently (1905)
the matter has been brought before the Highland and Agricultural
Society, chiefly through Montagu Baird, who with C. H. Babington was
instrumental in inducing the Board of Agriculture to publish a leaflet
recommending more careful methods of threshing barley. Close dressing
was at one time practised as a means of raising the bushel weight, and
thus giving a fictitious value to the barley. Immature barley feels cold
to the hand, has a greenish-yellow colour, and, when dry, a starved
wrinkled appearance. Over-ripeness in barley is distinguished by a white
dead appearance of the corn. Mature or dry grains slip through the
fingers more readily than unripe or damp ones. The contents of the
endosperm should present a white friable or mealy appearance when the
corns are bitten or cut in two with a penknife. The condition of the
grain may be determined by means of a mechanical cutter, which cuts a
certain number of corns (fifty or more) at one time. Some cutters are
constructed to cut the corns transversely, others to cut them
longitudinally. The so-called transparency test may be used for the same
purpose. It is carried out in an apparatus known as the diaphanoscope,
which consists of a box fitted with a sliding tray, furnished with a
certain number of shuttle-shaped holes (usually 500), each of such a
size as just to hold a barleycorn longitudinally. Into the portion of
the box below this tray an electric lamp is placed, and the corns are
looked at from above. Thoroughly mealy corns are opaque, whilst steely
corns are transparent. When certain portions of a corn are steely, these
present the appearance of lakes. By this means the percentage of mealy,
steely, or half steely corns in a sample may readily be estimated.
E. Prior points out that steeliness of barley is of two kinds, one of
which disappears after the grain has been steeped and dried, and
therefore does not necessarily influence the malting value of the
sample, and the other which is permanent, and therefore retards the
modification of the corn. He proposed to determine what he called the
coefficient of mellowness of a sample of barley by means of the
formula:--
(M1 - M)100
A = ----------- + M,
100 - M
in which A is the degree of mellowness, M is the percentage of mealy
corns in the original barley, and M1 is the percentage of mealy corns
after steeping and drying the barley. Prior points out that, generally
speaking, the degree of mellowness varies inversely as the proteïn
content.
The physical differences between steely and mealy grains were first
investigated by Johansen, who arrived at the conclusion that mealiness
is always accompanied by the presence of air spaces in the endosperm.
Munro and Beaven confirmed and extended this. Their conclusions are as
follow: "Mealy grains have a lower specific gravity than steely
grains, and contain a larger amount of interstitial air. The total
nitrogen content of mealy grains is less than that of steely grains.
Steely grains contain a relatively high proportion of nitrogenous
substances soluble (a) in 5% salt solution, and (b) in alcohol of
specific gravity 0.9. Mealy barley modifies better than steely during
germination. The process of drying damp and under-matured barley
intact at 100° F. produced an apparent mellowing or maturation. Other
things being equal, maturation, which is physiologically a
post-ripening process, is correlated with the mealy appearance of the
endosperm." H. T. Brown and his collaborators point out that thin
sections of steely corns when examined under the microscope no longer
exhibit a translucent appearance, but show the mealy properties as
completely as if they had been cut from a mealy grain, and they
suggest that in a steely corn the whole of the endosperm is under a
state of tensile stress which cannot be maintained in the thin
sections. If, however, a thin section of a steely barley be cemented
to a slide with Canada balsam and then pared away with a razor,
steeliness and translucency may be preserved even in the thinnest
sections. The mealy appearance in the endosperm of barley is assumed
to be a direct consequence of the formation of interspaces around the
cell-contents and within the cell walls. Under ordinary conditions it
is conjectured that these interspaces are filled with air, but it is
pointed out that they can also be produced under circumstances which
suggest that they are at times vacuous or partly so. According to the
last-mentioned authors they appear to originate from a system of
stresses and strains induced within the endosperm by its gradual loss
of water, a break of continuity taking place which gives rise to these
interspaces when the cohesive power of the heterogeneous cell-contents
falls below a certain point. It is further suggested by them that the
most important factor in producing the stresses and strains is
probably the shrinkage of the starch granules as their water content
is reduced from, say, 40 to about 15%. It is pointed out, however,
that actual discontinuity in the cell-contents can only take place
when the tensile strength of the protoplasmic matrix in which the
starch granules are embedded has been surpassed, and this being so it
might be anticipated that those cells which contain the larger amount
of proteïn material would probably best resist the internal stresses
and strains, a deduction in close agreement with observed facts,
steely grains being as a rule richer in proteïn than mealy grains.
Brown and his co-workers determine the coefficient of mealiness of a
barley as follows: Five hundred corns are cut transversely in a corn
cutter and the percentage of mealy, half mealy and steely corns is
noted. The number 100 is taken to represent complete mealiness, 1
complete steeliness, and 50 the intermediate class. If the percentage
of each class be multiplied by its special value, and the sum of the
products divided by 100, the result is the coefficient of mealiness.
By steeping and drying a very steely Scottish barley, the coefficient
of mealiness was raised from 29.7 to 87.1, whilst concurrently the
specific gravity fell from 1.417 to 1.289.
Barley even of the same kind varies widely in its chemical composition,
but on an average the proximate constituents of British malting barleys
be within the following limits:--
Moisture 18 --12 per cent.
Nitrogenous matters expressed as proteïns 8 --15 "
Fat 2 -- 2.5 "
Starch 60 --65 "
Sugars 1.5-- 2.0 "
Gums 1.7-- 2.0 "
Fibre (cellulose) 5 -- 7 "
Ash 2 -- 2.5 "
Any sample of barley which contains more than 20% of moisture would be
considered damp. The late Professor Lintner expressed the view several
years ago that a good malting barley should not contain more than 10% of
proteïn, but R. Wahl asserts that in America six-rowed barleys
containing a far higher percentage of proteïn are used successfully,
indeed preferably, for malting purposes. The only precise knowledge we
possess of the proteïn compounds of barley is due to the researches of
T. B. Osborne. According to this observer, barley contains the
under-mentioned compounds of this class in the following proportions:--
Soluble in water / Leucosin (albumin) \ 0.30 per cent.
\ Proteose /
Soluble in salt solution: Edestin (globulin) 1.95 "
Soluble in 75% alcohol / Hordeïn 4.00 "
\ Insoluble proteïn 4.50 "
-----
Total 10.75 "
It should be pointed out here that the above are only average values
for the particular samples of barley investigated. Undoubtedly the
nitrogenous constituents of different barleys vary widely in nature as
well as in amount.
Raw barley contains enzymes, thus diastase of translocation, so called
by Horace T. Brown and G. H. Morris, and catalase (H. van Laer).
Proteolytic enzymes appear only to arise with the beginning of
germination; but it has been asserted that raw barley contains
proenzymes (zymogens), which can be rendered active by treatment with
dilute lactic acid at an appropriate temperature. The action of the
diastase of raw barley on starch has been studied by Julian L. Baker.
Barley should not be cut until it is properly ripe, but over-ripeness is
much more to be guarded against by the maltster than premature cutting,
as it is accompanied by a loss in germinative power. Moreover, unripe
corn may to a certain extent be matured in stack, whilst a great
improvement in germinative capacity is frequently produced by sweating.
Very wet seasons are prejudicial to the ripening of the grain, and when
the latter is stacked in too moist a condition it is apt to become what
is known as mow burnt. Especially is this the case with barleys
containing large percentages of nitrogen and of high enzymatic
activities. Such barleys are denoted "warm" by M. Delbrück from their
tendency to heat when stored in a moist condition. The effect of this
heating is exhibited in the corns becoming black and discoloured at the
tips; they are then said to be magpied. Even in an otherwise dry season
a large amount of rain during harvest causes the corns to become
"weathered," whilst some of them begin germinating and rot. At the same
time heavy dews at night whilst the barley lies cut in the field, or
even a sprinkling of rain, assists in mellowing the grain, which often
in consequence works the more freely on the malting floors. Properly
harvested barley is all the better for remaining in stack for two or
three months, as was the practice in former years; if, however, it has
been stacked too wet the sooner it is broken down the better.
It is difficult to give any specific test for ripeness, but a series
of observations has been made by H. T. Brown and F. Escombe. Samples
of barley were taken from the field on the 20th, 24th and 29th of
July, and on the 2nd, 6th and 10th of August, and preserved in spirit
so that they remained in the same state as when they were gathered.
Sections were then cut of these corns, when it was found that the
progress of maturation is attended by deformation and ultimate
disintegration of the cell nuclei. The change which is denoted by the
term nuclear senescence is said to begin in the starch-containing
cells, near the periphery of the corn, immediately underlying the
layer next to the aleurone layer. This deformation is followed by
complete disintegration of the nucleus, and at the end of seven or
eight days nearly the whole of the endosperm has been involved. Brown
and Escombe state that when this nuclear test is properly applied it
stamps as immature those corns in a sample which are manifestly unripe
owing to premature desiccation as well as those in which the ratio of
nitrogen to carbohydrate is unduly high, owing to an excess of
nitrogenous manure in the soil, or to sparser sowing with its
consequent reduction of root competition. This method, interesting
though it be, is not fitted for practical use, and the agriculturist
must rely as heretofore upon empirical methods for deciding whether or
not the grain has attained ripeness or maturity.
The bushel weight is a useful criterion in arriving at an opinion
regarding the value of a sample of barley; but in basing judgment upon
this factor regard must be paid to the fact already mentioned that if
the grains be dressed closely the bushel weight is increased. The
reason of this is that with the removal of the awns the corns pack
more closely together. The best British malting barleys should weigh
52-56 lb. per bushel, the standard weight for malting barleys being 56
lb.
During the storage of barley access of air is necessary, otherwise the
grain dies from asphyxiation. Sound barley after being kiln-dried
retains its vitality for a number of years; but the statement that the
corns found in the Egyptian mummy cases, in which they had remained for
several thousands of years, were still capable of germination, is
contrary to modern experience. Moisture must also be carefully excluded,
as it initiates germination in a few cells only of the endosperm and
causes heating. A constant repetition of wetting such as may take place
on account of alterations of the atmospheric temperature, which causes
moisture to be deposited, in the form of dew, may ultimately destroy the
vitality and foster the growth and development of mould fungi which
usually grow on broken and damaged corns. In this connexion the
advantage of screening and sweating of barley before storing it will be
apparent (see below).
An immense amount of damage is caused to the grain, during storage, by
various insects, one of the most destructive of these being the common
weevil (_Calandra granaria_). When fully developed this insect
measures (1/6)th to (1/8)th of an inch in length, and is of a bright
chestnut colour. The larvae are fleshy legless grubs, shorter than the
perfect insect, with a series of tubercles along each side of the
body; the head is round with strong jaws. The pupa is white, clear and
transparent, showing the form of the future weevil. The female bores a
hole in the grain with her snout and deposits an egg. The larva when
hatched lives on the contents of the grain and undergoes its changes
therein. Windisch asserts that only barley which has ripened in the
granary is attacked by weevil. Grain which is only slightly attacked
should be kilned at a temperature of 122° F., which destroys the
weevil in all stages of development. To detect weevil in a sample of
barley, the grain should be spread out on a sheet of white paper in
bright sunlight. If weevils are present they soon appear, and betake
themselves to a position outside the sunlight, to which they are
averse. Treatment of the grain with carbon bisulphide has been
suggested as a means of destroying weevil; even if efficacious,
however, such a process could not be recommended on account of its
danger, carbon bisulphide being highly inflammable. The only practical
means of ridding a granary or shop of weevil is to clear out all the
grain and leave it empty for a year or more.
The vitality of barley may be determined by causing a sample to
germinate in any of the well-known forms of apparatus devised for that
purpose, and counting the percentage of germinating and idle corns. The
germinative capacity of a sample of barley may frequently be raised by
sweating (see below), which, as already mentioned, brings about a kind
of artificial maturation.
_Malting._--There are two systems of malting used in England: floor
malting and pneumatic or drum malting. These systems will be described
separately.
A floor malting consists of a rectangular building of several storeys,
having the cisterns at one end and the kilns at the other. The uppermost
floor is devoted to barley.
[Illustration: FIG. 8.--Longitudinal section of 200 quarter malting at
Mortlake. (Julian L. Baker, architect.)]
Figure 8 shows a longitudinal section of Messrs Watney, Combe, Reid &
Co.'s 200 quarter malting at Mortlake. The barley is carried to the
top of the building by the elevator A, where the screening and
dressing machinery is situated. After leaving these machines the grain
is conveyed on bands to the barley floors B and C. The floor C
contains also the steeping cisterns. The six working floors are D, E,
F, G, H, K. The floors are ventilated by louvres, N, N, N. The
cisterns are connected to the floors by means of plugs. The "pieces,"
as they are termed, of germinating barley are gradually worked along
the floors to the kilns M, M, on to which they are loaded by rotary
bands. The fire-places O, O, are arranged so that the draught may be
easily controlled. The hot air and products of combustion pass up the
shafts P, P, to the hot-air chamber R, R, where they strike the baffle
plates S, S. These plates disperse the hot air and gases evenly
beneath the kiln floors T, T, through the green malt. After drying and
curing, the malt is allowed to cool and is then carried by bands to
the floor U, where by suitable machinery the coombs or rootlets are
removed. The finished malt is stored in the bins V, V, V.
On arrival at the malting the barley has to be put through the following
operations seriatim: receiving, hoisting and weighing, rough screening,
drying and sweating, storing until required for use, screening, grading
and removing broken corns, steeping, couching, flooring, withering,
drying and curing, dressing and polishing, storing, weighing, sacking
and discharging the finished malt.
In sweating barley the temperature should not be allowed to rise above
120° F.; it is usually conducted at 100° F.; and subsequently the barley
should be stored for some weeks before it is steeped.
The capacity of a malting is described by the number of quarters which
are put through it every four days. A fifty quarter malting does not
merely mean that the cisterns have a capacity of fifty quarters, but
that this quantity of barley goes through the house every four days. The
average time the germinating barley is on the floors is twelve days,
and, as a rule, kilning occupies four days. If, as sometimes happens,
the malt has to be kept on the floors thirteen, fourteen, fifteen days,
or even longer, the malting is not being worked at the capacity under
which it is described, and the kilns may remain unused for a day or
more. Conversely, when the malt is loaded at less than twelve days, a
day or two has to be missed in steeping. In the former case when the
kilns are not being used for drying and curing malt, advantage may be
taken to utilize them for sweating barley.
Steeping cisterns were formerly rectangular vessels, of slate, brick or
cement, from which the barley had to be discharged by shovelling it out.
The forms approved most at the present day are conical and constructed
of iron; they have arrangements at the apex of the cone, the lower
portion, for discharging the grain by gravitation. The steeping period
ranges from 48 to 70 hours; it varies according to the kind of barley,
and the time of the year. In some of the older maltings there are no
arrangements for heating the steep water, and in the winter steeping has
occasionally to be performed with water at a temperature near its
freezing-point. Steeping should be carried out at a temperature as near
as possible to 55° and not higher than 60° F. The usual practice is to
fill the cistern up to a certain height with water and throw the barley
into it, stirring it until it is about level; the heavy corns will then
sink directly to the bottom, whilst the light corns and refuse float on
the surface and may be skimmed off. During the time the barley remains
in the cistern it is usual to change the steep water two or three times,
generally at intervals of twelve hours or tides. The advantage of this
is not merely to keep the grain fresh and sweet, but to bring it into
contact with the air during the time it is taking up water. Aëration of
the steep has long been recognized in Germany as promoting germination,
and several arrangements are on the market enabling air to be passed
through the grain while it is in the cistern. It has been recommended by
Graham, Stopes, Moritz and Morris, and experimental evidence as to its
beneficial effects has been published by Windisch, Bleisch, Will, and
Baker and Dick. When the corn is steep ripe it contains some 60% of
water. Steeping does not consist, however, merely in the imbibition of
a certain amount of water; in order to bring about germination this
water must remain within the corn a certain length of time. Thus,
although it is quite possible to force the necessary amount of water
into the grain in less than the 48-70 hours usually taken up by the
steeping process, the grain is not steep-ripe until certain changes
initiated by the water have taken place, and these require time for
their completion. The following average data are useful to remember in
connexion with the steeping process:--
Amount of water in steep-ripe barley (about) 60%.
Matter removed from barley during steeping (about) 1.5%.
Increase in volume of barley due to water absorption (about) 18-20%.
There has been much discussion as to the influence of saline matters
in water on the steeping process. The late Professor Lintner stated
that common salt in water tended to extract the nitrogenous
constituents of the grain, but impeded its germination. Mills and
Pettigrew found that waters containing calcium salts extracted a
minimum of nitrogenous compounds from the barley; they also came to
the conclusion that the esteem in which the Lichfield water is held
for steeping purposes is due to the presence of nitrates which, they
assert, have a stimulating effect on the subsequent germination of the
grain. The writer has added lime-water to the extent of one-third of
the total volume of water at the first change, believing it to promote
regularity of germination. Bearing in mind, however, the observations
of Adrian J. Brown, that the barleycorn is enclosed in a membrane
permeable to water but impermeable to most salts, it is difficult to
see how the saline constituents of water can have any effect except in
removing matter from the external portions of the grain and on those
corns which are broken. The apparent beneficial effect of lime-water
in the steep is probably entirely due to the removal of matters from
the husks or paleae.
Malting floors may be constructed of cement, tiles or slate, the two
former being preferable to the latter. Ford, in 1849, recommended 200
sq. ft. per quarter of barley steeped as the area of the working floors,
and he was quite convinced of the necessity of allowing ample floor
room, so that the grain could be worked on the slow, cool system.
Subsequently, however, maltsters reduced their floor area, and put the
grain rapidly through the malting, thus producing what is termed
"forced" malt. This kind of malt was, however, condemned by practical
brewers, and a chemical test whereby forcing could be detected having
been devised by E. R. Moritz and G. H. Morris, maltsters have been
compelled again to increase the area of their working floors. At the
present time the approved area may be placed at 175-200 sq. ft. per
quarter of barley steeped. The area is, however, largely ruled by the
kind of barley to be malted.
After the barley has been thrown out of the cistern it is made up in a
rectangular heap 16-20 in. deep, called the "couch"; the object of this
is to enable it to gather heat and so start germinating. It usually
remains in couch for 12-24 hours, until in fact the interior portion of
the heap registers a temperature of about 60° F. During the days of the
malt tax the exciseman gauged the quantity of the barley while it was in
the couch. After couching the barley is spread thinly and evenly on the
floor, forming what is known as the young floor or No. 1 piece. The
first visible sign of germination is the sprouting of the rootlet,
termed "chitting," and this occurs either while the grain is on the
couch or on the young floor. As already mentioned, it may be quickened
by aerating the grain in the cistern. From the time the barley is first
cast out of the cistern up to the stage of the young floor, or No. 1
piece, it has a pleasant ethereal odour resembling apples. Drs Thomson,
Hope and Coventry stated in the earlier part of the 19th century that
they distilled "spirits" from germinating barley at this stage. In the
light of our present knowledge it would not be surprising if alcoholic
fermentation were proved to occur within the grain at this stage, since
intramolecular or anaerobic respiration in certain vegetables has been
found to be due to alcoholic fermentation.
The thickness at which the young floor is spread depends upon the
outside temperature and the nature of the barley. If the weather be
warm, or if there be a tendency for the barley to heat, the piece must
be spread all the thinner. At this stage the grain loses its external
wet appearance. When spread too thickly the grain will begin to sweat,
and the rootlets will be thrown out suddenly and unevenly. As a rule,
under these circumstances, the rootlets will be long and thin, when they
are said to be "wild." A piece which has been allowed to get into this
condition must at once be spread thinner. If the sweating has not
continued long, the harm done may be confined to increased loss by
respiration. The young floor is usually turned with a plough twice
during twelve hours, and it may be forked between whiles, but no hard
and fast rule can be laid down as to when this is necessary; it must be
left to the maltster's judgment, as it depends entirely on what is going
on within the grain. The object of turning is in the first place to
aerate the grain and freshen it, secondly to check excessive rise of
temperature, and thirdly to promote evenness of growth. Too frequent
turning is not to be advised. After remaining four days on the young
floor three or four rootlets should have appeared, and the acrospire
should have begun to grow up the back of the corn. The apple-like odour
of the piece then gives place to one resembling that of the common rush,
and this should continue the whole time that the malt remains on the
floor. On the fifth day the piece is next moved to No. 2 position, a
stage nearer the kiln. It is here that sprinkling is resorted to when
necessary. The amount of sprinkling and the time it is given cannot be
exactly prescribed. The amount may vary from two to five gallons per
quarter, and it should only be given when the rootlets, which ought to
be short and curly, and five or more in number, show signs of losing
their freshness. If an excessive amount of sprinkling be given forced
growth ensues. It is preferable not to add the whole of the water at one
time, but to divide it over two lots; and immediately after the piece
has been sprinkled it should be thoroughly and carefully mixed,
otherwise some of the grain will receive an undue proportion of water.
When all the sprinkling water has been given to the piece, which as a
rule should not be done later than at the sixth or seventh day of
flooring, the temperature should be kept down to about 55° F. by
turning. Too frequent turning may, however, detach the rootlet, and it
may cause the grain to lose its vitality prematurely, so that growth of
the acrospire stops.
By about the eighth day of flooring the acrospire should be about
three-quarters up the corn. After this the germinating corn is moved
forward to No. 3 piece, which is at first spread as thinly on the floors
as in the previous pieces. Here it gradually dries and incipient
withering of the rootlets sets in. The only treatment which is now given
to the grain is to heap it up thicker and thicker by degrees until it is
ready for loading on the kiln. This increase in thickness of the piece
(now called the old piece) should not be too sudden, especially if the
grain be fresh in appearance and contain a large quantity of water. When
the piece is thickened up to say 10 in. in depth, while it is in a very
moist condition, heating and sweating take place, with additional growth
of acrospire and rootlet. Under such forcing conditions a large
production of sugar and degradation of the proteïns will take place.
When, however, the moisture has been gradually reduced before thickening
up, the rootlet dies off; and although increase of temperature may
occur, this is accompanied by little or no further growth of the
acrospire, action being confined to the mellowing of the grain by the
enzymes. When the malt is ready for loading on the kiln it should be
possible to break down the contents of each corn between the thumb and
finger. Opinions differ as to what the final temperature on the
withering floor should be. If the moisture content of the malt be about
50%, the piece must be kept thin to avoid sweating. But under these
conditions mellowing does not occur, hence the necessity of reducing the
moisture content gradually after the last sprinkling water has been
given. When the process has been conducted properly the temperature of
the old piece may be allowed to rise as high as 70° F. during the six
hours previous to loading. The moisture content of the green malt when
loaded should not be much above 40%.
The endosperm of green malt which is ready for the kiln should be soft
and mealy, and should not exude moisture when pressed between the
thumb-nails, but should crumble and disintegrate to a chalky mass having
little or no adhesiveness.
The foregoing observations are not to be regarded as hard and fast
rules, but they are simply intended to give some indications of the
malting process when it proceeds on normal lines; it may be that on
account of the presence of damaged corns the piece begins to develop
mould by about the tenth day, and it then has to be kept thin and
sometimes even loaded on kiln prematurely.
The malt made for grain distillers, in which a high diastatic activity
is required, is manufactured on quite different lines from those above
indicated. It is often sprinkled late, and loaded on kiln often in a
sodden condition. In some cases sprinkling on kiln is resorted to, but
it is doubtful if this leads to the desired object. Other things being
equal, the smaller the corns--i.e. the greater number of embryos in a
given weight--the higher the diastatic activity of the malt. In
selecting a barley for the production of highly diastatic malt, the
diastatic power of the original raw grain is a factor of great
importance.
_Kilning._--When loaded on kiln, malt intended for brewing ale and stout
is, if properly withered, in a moribund condition; nevertheless, during
the first stages of the kilning process a certain amount of vital
activity is manifested, and the malt undergoes mellowing by the action
of enzymes on the contents of the endosperm. If the malt be loaded while
the rootlets appear fresh on account of the presence of too much
moisture, rapid growth of the acrospire ensues, giving rise to overshot
corns, known in Germany as "hussars." To check this the moisture must be
rapidly removed by the passage of large volumes of air through the malt.
But under such circumstances mellowing does not occur. The ideal
conditions of kilning are when the malt has been properly withered on
the floors before loading, and, assuming that drying and curing occupy
four days, that 25-30% of the moisture be removed very gradually, this
occupying the first three days, at the end of which the malt is said to
be hand-dry. The thickness at which the malt is spread on the kiln
should not exceed 7-8 in., and until hand-dry (that is to say, reduced
to a moisture content of 12-15%) it should not be turned; if moved at
all (and that only is necessary when reek occurs), it should only be
lightly forked. The rate at which the temperature is raised depends
largely on the kind of malt to be made and the construction of the kiln.
If high flavour and colour are required, these are produced by keeping
the malt for several hours near a temperature of 160° F. while it still
contains 12-15% of moisture. If more than this amount of moisture be
present when the temperature reaches the limit just mentioned, the
conditions known as stewing would obtain, with the result that "forced"
malt would be produced. A certain amount of colour is produced at the
final temperature to which the malt is raised; but when such means are
relied upon for the production of the greater part of the colour,
reduction of extract and deficiency of flavour follow, the colour being
then almost exclusively the result of caramelization of the
carbohydrates.
The so-called curing stage constitutes the last part of the kilning
process, and the malt must then be turned frequently to ensure
uniformity of action. Mechanical turners are exceedingly useful for this
purpose. Curing in a drum, as in the so-called pneumatic malting process
(see below), also effects satisfactory curing.
The following table will give an idea of the kilning temperatures
usually employed for the three kinds of malt mentioned, but it must be
remembered that these temperatures are largely regulated by the
construction of the kiln and the amount of draught available. In this
connexion it may be mentioned that the final curing temperature is not
necessarily a criterion of the tint of the malt. A malt may have been
finished off at a very high temperature and still be a pale malt,
provided the moisture percentage has been sufficiently reduced in the
initial stages of kilning.
Running
Pale Malt. Ale Malt. Amber Malt.
1st day temp. 90-100° F. 90-100° F. 90-100° F.
2nd " " 100-120 100-120 100-130
3rd " " 120-130(10 hrs.) 120-130( 6 hrs.) 130-150( 6 hrs.)
3rd " " 130-180( 8 " ) 130-150(12 " ) 150-160(12 " )
3rd " " 180-190( 6 " ) 150-180( 6 " ) 160-180( 6 " )
4th " " drop to 170(12 " ) 180-190(12 " ) 180-200(12 " )
4th " " 190-200( 6 " ) 200-220( 6 " )
4th " " drop to 180( 6 " ) drop to 190( 6 " )
The average laboratory values obtained from malts of the descriptions
after about two months' storage should be as follows:--
Running
Pale Malt. Ale Malt. Amber Malt.
Extract per standard quarter of
336 lb. 95-98 lb. 94-96 lb. 94-96 lb.
Moisture about 2.0% in each case
Diastatic activity (Lintner) 30-35 20-30 8-10
Tint (Lovibond 52 series neutral) 3-5 6-8 20-25
_Metabolic Changes._--All through the malting process metabolic changes
are proceeding, in which both carbohydrates and proteïns are concerned.
In its resting stage the embryo of a barleycorn is generally free from
starch; as soon as germination sets in, however, starch appears in the
scutellum, while the amount of sucrose there present increases, these
being apparently formed from maltose originating from the action of
diastase on the starch of the endosperm. Sucrose also augments in the
aleurone layer, but starch is never formed in the aleurone cells. These
changes occur when the malt is first loaded on kiln; indeed, at no part
of the malting process is there greater physiological activity.
Kilning has been specially studied by J. Grüss, who divides the process
into four stages, the first being that at which the temperature limit is
113° F. It is characterized by a continuation of the living processes,
especially growth of the acrospire, which, as already stated, proceeds
too far if the malt be loaded too wet. In any case the rootlet dies
away. The metabolism of the carbohydrates already mentioned is
accompanied by that of the nitrogenous constituents, the reserve proteïn
of the sub-aleurone layer being attacked by proteolytic enzymes and
broken down into simpler compounds. This is a most important matter from
the point of view of the brewing value of barley, for the degradation
products of the proteïns are necessary constituents of wort as yeast
food. Moreover, unless proper modification of these proteïn bodies
occurs it is impossible to produce tender malt. A barley which contains
a high percentage of reserve proteïn is as a rule unfitted for malting
purposes, and indeed, the higher the proteïn content the greater the
difficulty the maltster experiences in dealing with it. Proteïn
hydrolysis requires the presence of a certain amount of moisture, and if
this be removed too rapidly by a forced draught at the early stages of
kilning the proteolytic enzymes cannot perform their function. If, on
the other hand, the grain be loaded in too moist a condition, and the
temperature be raised too quickly, the proteolytic enzymes lose their
activity and the proteïns remain for the most part unattacked. When
germination is allowed to proceed on the kiln too great degradation of
the proteïn occurs, and the malt is liable to produce fretty beers, on
account of the presence of an excessive amount of nitrogenous nutritive
matter, which leads to the development of disease organisms.
The second stage of the kilning process, according to Grüss, is that at
which the temperatures range from 113° to 167° F. The life of the corn
is now suspended, but enzymatic processes continue. The starch is
further saccharified, and the dividing line of the aleurone layer at the
furrow is attacked, as are also the cell walls of the endosperm, which
are still intact, these being partially converted into gummy substances.
This change, however, also requires the presence of a certain amount of
moisture. If too much air be passed through the malt at this stage the
above-named dividing partition of the cell walls is not attacked. The
air may expand the grain to some extent and produce malt of a low bushel
weight, which, however, is not properly modified and cannot give
satisfactory results in practice.
During the third stage of kilning, an enzyme, which Grüss claims to have
recognized, and which he denotes spermoxidase, is said to exert its
activity.
Schönfeld has confirmed the discoveries of Grüss by practical
experiments.
_Fuel._--The fuel used for drying and curing malt is either anthracite
or coke, and the greatest care is necessary in selecting it on account
of its liability to contain arsenic, which is to a greater or less
extent an invariable constituent of all coal. The fuel used for
malting purposes should not contain more arsenic than (1/20)th grain
per lb. Gas coke should on no account be used, unless it has been
proved to be sufficiently free from arsenic; but the best oven coke
frequently contains so little arsenic that it may be employed with
perfect safety, especially if it be mixed with a proportion (e.g. 5%)
of milk of lime, which retains the arsenic as calcium arsenate. In
Germany malt is, as a rule, dried and cured with hot air, whilst in
Great Britain the products of combustion are passed through the malt,
as it is believed that they exert a beneficial influence on the
flavour. The proportion of fuel used for drying and curing malt varies
according to the quality of the fuel and the construction of the kiln,
but on an average it may be placed at 50-80 lb. per quarter.
[Illustration:
[From Sykes & Ling, _Principles and Practice of Brewing_ (1907),
Charles Griffin & Co., Ltd.]
Fig. 9.--Diagrammatic view of pneumatic malting, showing pneumatic
washing and steeping cisterns.]
_Storing._--After the malt has passed through the curing stage it is
generally heaped up for a few hours. This is believed to increase its
flavour. The malt is then stripped from the kiln, and the rootlets,
technically known as the coombs, are removed. Formerly this was
effected by workmen treading the malt, who wore heavy boots for the
purpose. At the present time, however, the rootlets are usually
removed by machinery, special forms of which have been devised for
this as well as for dressing and polishing the malt. It is the custom
of some maltsters to store malt with the rootlets still attached; but
this is an objectionable practice, since malt coombs attract moisture,
and the presence of more than 3% of moisture in malt produces the
condition known as "slackness." When the malt is packed in bin it is
often covered with a layer of coombs, which then prevent access of
atmospheric moisture. Malt, to preserve its good qualities intact,
should be stored in bins made as nearly as possible air-tight, and it
should never be placed in bin until it is quite cool. It is probably
wrong to store malt in bins adjacent to the kilns, where it is kept at
a higher temperature than that of the surrounding atmosphere. During
storage of the malt a kind of mellowing occurs, the mechanism of which
is not understood. It is, however, known by practical brewers that the
best results cannot be obtained when new malt is used.
_Premature Malting._--Several years ago Galland suggested germinating
barley in a drum, his idea being to do away with handling of the
grain, and also to be independent of changes of atmospheric
temperature. The latest development of this system, the so-called
Galland-Henning process of pneumatic malting, has been improved by Mr
R. Blair Robertson, and a diagrammatic view of the interior of one of
these maltings, showing the drums and conical steeping cisterns, is
shown in fig. 9.
The drums are provided with a perforated channel for the passage of
air through the malt, which is packed in the annular space between
this channel and outside wall of the drum. Each drum is capable of
revolving on its axis, and there are arrangements for passing either
moist, saturated or dry air through the malt. The system as now
improved is capable of producing some of the best malt, especially if,
after germination has been completed in the drums, the green malt is
loaded on an ordinary kiln and the initial stages of kilning (see
above) conducted in the usual way; the curing, however, may be carried
out successfully in a special form of drum.
_Yield and Weight._--The malting process is attended with a certain
amount of loss of dry substance of the barley, as follows:--
In the steep 1.5 to 2.0%
By respiration on floors and on kilns 3.0 " 5.0%
Coombs 3.0 " 4.0%
--- -----
Total 7.5 " 11.0%
In addition to this, barley, as already mentioned, contains from 15 to
20% of moisture, whereas finished malt contains 1 to 2%. The total
loss in weight which barley undergoes in the malting process may be
put down at from 17 to 28%. Since, however, malt is lighter than
barley (and the quantity of both was in former years measured
exclusively by volume), it frequently happens that a given number of
quarters of barley yields a larger number of quarters of finished
malt. When this happens it is usual to speak of an increase having
been obtained. At the present time weight replaces measure for both
barley and malt, and although it is usual to speak of the quantity of
grain in terms of quarters, what is meant is not the measured quarter,
but so many weighed standard quarters. The standard quarter for
English malting barley is 448 lb. and for malt 336 lb. From this it
will be seen that when a given number of weighed quarters of barley
yields the same number of quarters of finished malt, the actual yield
is 75%, and there is then said to be neither increase nor decrease. As
a rule, in practical working the yield of malt varies from a 4%
decrease to a 10% increase, corresponding to an actual yield on the
original barley of 72 to 82.5%.
J. Baverstock, an old writer, says that finished malt should weigh
one-fifth less than the barley from which it is produced. This
corresponds to a malting increase of about 7%, which is a high yield.
As a rule, foreign barley will give a greater malting increase than
English barley, because, on the one hand, the former usually contains
less moisture than the latter, and, further, because there is less
loss on the floors by respiration and rootlet growth.
The yield of malt from barley may be determined in the laboratory in
an extremely simple manner. Since every grain of barley must yield a
grain of malt, if we know the respective weights of a definite number
of barley and malt grains, provided that this number is large enough
to represent the average, then obviously this gives the data requisite
for calculating the yield of malt from barley. The number of corns the
weight of which is determined for this purpose is usually 1000, and if
the weight of this number be determined on several different 1000
corns, the average will closely approximate to the truth. Instead of
counting the corns by hand, an instrument may be used for this
purpose.
If 1000 corns of a barley were found to weigh 42 grammes, and 1000
corns of a finished malt from the same barley 32 grammes, then the
yield of malt is (32 × 100)/42 = 76.1, this corresponding to a 1%
increase. Assuming that the moisture content of the barley was 15% and
that of the finished malt 2%, 100 grammes of malt will contain 2
grammes of moisture, and 76.1 grammes will contain (76.1 × 2)/100 =
1.5 grammes moisture; therefore 76.1 grammes of malt contain 76.1 -
1.5 = 74.6 grammes of dry matter. This was obtained from 100 - 15 = 85
grammes of barley dry substance. Hence 100 parts of barley dry
substance will yield (74.6 × 100)/85 = 87.7 corresponding with a loss
of dry substance equal to 12.5% of the dry substance of the barley, or
with a loss of 10.7% on the barley containing 15% of moisture.
The results obtained by this method of laboratory control when it is
accurately carried out agree very closely with those deduced from the
practical results of weighing the barley, malt and coombs in the
malting.
_Special Malts._--In addition to the kinds of malt considered in what
precedes, there are others mostly used for imparting specific flavours
and colour to beers and stout. These are crystal malt, imperial malt,
brown or blown malt, and black or roasted malt. Crystal malt is grown
for a shortened period on the floors, and then placed in a wire
cylinder, which is rotated over a fire so that it is dried at a very
high temperature. The weight per quarter is from 250 to 280 lb.
Imperial malt is dried off on an ordinary kiln at a final temperature
of 240-270° F., but it is not allowed the usual length of time on the
withering floor. It is placed on the drying kiln in a layer not
exceeding one inch and a half in thickness. A moderate heat from burnt
wood is first applied until the bulk of the moisture has been driven
off, when the temperature is suddenly raised so that the grains swell
some 25% and the malt takes up a strong empyreumatic flavour from the
products of combustion. This kind of malt weighs 270-300 lb. per
quarter. Black or roasted malt is prepared by roasting malt in a
cylinder. Ford states that perfectly malted corn gives a colour of
less intensity and permanence than does partially malted corn, and
this has been confirmed by other observers. A certain quantity of the
so-called black malt is actually made from raw barley, but this gives
a product of inferior flavour. The weight per quarter of black malt
varies as much as from 215 to 290 lb.
_Valuation._--For the valuation of malt the following determinations
are usually carried out: Extract per standard quarter, moisture,
diastatic activity by the Lintner process, tint, and matters soluble
in cold water. The physical examination of malt is also a matter of
importance, inasmuch as direct evidence is obtained thereby of the
modification of the malt. Among the methods adopted for this purpose
may be mentioned counting the percentage of corns in which the
acrospire has grown up to one-half, two-thirds and three-fourths the
entire length of the corn. In properly made malt the modification of
the endosperm should proceed _pari passu_ with the growth of the
acrospire. The sinker test is also useful when carried out in an
intelligent manner. Those corns which sink in water and lie flat are
improperly modified. Normal malt has a specific gravity less than
water and the corns have equal density throughout; consequently they
float horizontally in water. In forced samples the proximal ends are
frequently lighter than the distal ends, and the corns float
horizontally in water, with the germ directed upwards. The latter,
however, may in some cases fill with water, and the corns lie flat or
sink. This is a characteristic of over-modified malt. It will be seen
from these remarks that it is essential to carry out the sinker test
under standard conditions. The modification of the malt may also be
determined by means of the diaphanoscope already referred to under
Barley.
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11, 380; J. Baverstock, _Treatise on Brewing and Malting_ (1824); E.
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Station (1894); H. Stopes, _Malt and Malting_ (1895); W. J. Sykes and
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