Barley even of the same kind varies widely in its chemical com position, but on an average the proximate constituents of British malting barleys lie within the following limits:— Any sample of barley which contains more than 2o% of mois ture would be considered damp. The late Prof. Lintner expressed the view several years ago that a good malting barley should not contain more than o% of protein, but R. Wahl asserts that in America six-rowed barleys containing a far higher percentage of protein have been used successfully, indeed preferably, for malt ing purposes. A summary of our knowledge of the nitrogenous constituents of barley and malt was published by H. F. E. Hulton in 1922. According to T. B. Osborne barley contains the under mentioned proteins in the following proportions:— 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 be ginning 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. According to Ling and Nanji the diastase of barley converts the a amylose constituent of starch into maltose and the amylo-pectin constituent into ar3 hexa-amylose.
Maturing and Storage.—Barley should not be cut until it is properly ripe, but over-ripeness is much more to be guarded against. 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. This results in the corns becoming black at the tips; they are then said to be mag pied. H. T. Brown and F. Escombe find that maturation is attended by deformation and ultimate disintegration of the cell nuclei. The change which is denoted by the term nuclear senes cence 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 disin tegration of the nucleus, and at the end of seven or eight days nearly the whole endosperm has been involved. 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 connection the advantage of
screening and sweating of barley before storing it will be apparent.
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 devel oped this insect measures to * of an inch in length, and is of a bright chestnut colour. The larvae are freshly 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 fu ture 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. 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.
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 consist° 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.
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 pol ishing, 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 ioo° F.; and subse quently 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 can be put through it every four days. A fifty quarter malt ing 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 12 days, and, as a rule, kilning occupies four days. If, as sometimes happens, the malt has to be kept on the floors 13, 14, 15 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 i 2 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 cur ing malt, advantage may be taken to utilize them for sweating barley.