220 TECHNOLOGY OF CEREALS At intervals the grain is mixed and turned to Clean, graded barley grain rovide more uniform growth opportunities, and to prevent the roots from matting together. As the embryo grows it produces hormones including Steeping gibberellic acid, stimulating production of hydro lytic enzymes in the scutellum and aleurone layer, leading to 'modificationof the starchy endo- Chit malt perm. The malting process is regulated by the initial choice of barley, the duration of growth the temperature, the grain moisture content Germination changes in the steeping schedule, and by use of additives. When modification is sufficient it is stopped by kilning the 'green malt,, that is, by drying and cooking it in a current of hot dry air The dry, brittle culms are then separated and the finished malt is stored. Dry malt is stable storage and, unlike barley, it is readily crushe Kilning The conditions of kilning are critical in deter mining the character of the malt: it can cause a slight enhancement of the levels found in green Finished malt malt or completely destroy it. Malt contains relatively large quantities of soluble sugars and nitrogenous substances and, if it has been kilned Milling at low temperatures, it contains high levels of hydrolytic enzymes. When crushed malt is mixed with warm water the enzymes catalyze hydroly Ground malt of the starch, other polysaccharides, proteins and nucleic acids accessible to them whether from FIG 9. 1 Diagrammatic summary of the malting process the malt or from materials mixed with it. Malt also confers colour, aroma and flavour to the Selected barley is'steeped', usually by immer- product. The solution of the products of hydrolysis sion in water, for a period chosen to achieve a extracted from the malt is the wort'. It forms particular moisture level. The water is drained the feedstock for fermentation for brewing or from the grain, which germinates. Conditions are distillation(Briggs, 1978 regulated to keep the grain cool (generally below One of the benefits derived from the applica 18C)and to minimize water losses. as the grain tion of technology in malting has been the reduc- germinates the coleoptile(acrospire) grows beneath tion in time required to produce satisfactory the husk and pericarp while the 'chit(coleorhiza, malts. The amount of time saved can be inferred root sheath)appears at the base of the grain, and from the diagrams in Fig. 9. 3. It is clear that is split by the emerging rootlets. Fig. 9.2 most saving has occurred during the present FIG 9. 2 Diagrammatic longitudinal sections through barley grains in the early I imbibed grain, 2. rootlets emerged, 3. Rootlets and coleoptile emerged om Briggs(1978), Barley (Fig. 1. 11). Reproduced by courtesy of Chapman and Hall Ltd220 TECHNOLOGY OF CEREALS Malting Clean, graded barley grains At intervals the grain is mixed and turned to provide more uniform growth opportunities, and to prevent the roots from matting together. As the embryo grows it produces hormones including gibberellic acid, stimulating production of hydro￾lytic enzymes in the scutellum and aleurone layer, leading to ‘modification’ of the starchy endo￾sperm. The malting process is regulated by the initial choice of barley, the duration of growth, the temperature, the grain moisture content, changes in the steeping schedule,and by use of additives. When modification is sufficient it is stopped by kilning the ‘green malt’, that is, by drying and cooking it in a current of hot dry air. The dry, brittle culms are then separated and the finished malt is stored. Dry malt is stable on storage and, unlike barley, it is readily crushed. Kilning Sprouts The conditions of kilning are critical in deter￾mining the character of the malt: it can cause a slight enhancement of the levels found in green Finished malt malt or completely destroy it. Malt contains relatively large quantities of soluble sugars and nitrogenous substances and, if it has been kilned at low temperatures, it contains high levels of hydrolytic enzymes. When crushed malt is mixed with warm water the enzymes catalyze hydrolysis of the starch, other polysaccharides, proteins and nucleic acids accessible to them, whether from the malt or from materials mixed with it. Malt also confers colour, aroma and flavour to the product. The solution of the products of hydrolysis extracted from the malt is the ‘wort’. It forms the feedstock for fermentation for brewing or distillation (Briggs, 1978). One of the benefits derived from the applica￾tion of technology in malting has been the reduc￾tion in time required to produce satisfactory malts. The amount of time saved can be inferred from the diagrams in Fig. 9.3. It is clear that most saving has occurred during the present 1 Steeping 7 “Chit malt” Germination 1 Green malt +-Ma1t + Milling Ground molt FIG 9.1 Diagrammatic summary of the malting process. Selected barley is ‘steeped’, usually by immer￾sion in water, for a period chosen to achieve a particular moisture level. The water is drained from the grain, which germinates. Conditions are regulated to keep the grain cool (generally below lS°C) and to minimize water losses. As the grain germinates the coleoptile (acrospire) grows beneath the husk and pericarp while the ‘chit’ (coleorhiza, root sheath) appears at the base of the grain, and is split by the emerging rootlets. Fig. 9.2. 0 1 2 3 FIG 9.2 Diagrammatic longitudinal sections through barley grains in the early stages of germination. 1. imbibed grain, 2. rootlets emerged, 3. Rootlets and coleoptile emerged. From Briggs (1978), Barley (Fig. 1.11). Reproduced by courtesy of Chapman and Hall Ltd