Malting of the barley grain to produce pale malt involves the imbibing of the barley with water (steeping) to a moisture content of 42–46%, a period of metabolic and physiological activity after germination and finally kilning with increasingly hot air to dry the malt to approximately 5% moisture, thus ceasing metabolic activity.
Malting is defined as the controlled germination of cereals, to ensure a given physical and biochemical change within the grain, which is then stabilized by grain drying. It is a process of forced germination, conducted in order to degrade starch molecules and to obtain certain levels of amylolytic and proteolytic enzymes which are important in brewing.
Three process steps are necessary to ensure that these changes occur:
*Steeping, to ensure good absorption of water by the grain (from 12% to at least 40% of moisture);
*Germination, to maintain embryo growth, enzyme synthesis and a limited endosperm breakdown; and
*Kilning, to ensure product stability.
Malting ensures the accumulation and release of a number of malt enzymes that degrade starch (αamylase, β-amylase, limit dextrinase, and α-glucosidase), cell wall non-starch polysaccharides (β-glucanase and xylanases), lipids (lipase and lipoxygenase), and enzymes that degrade and release proteins (endo-proteinases and exo-proteinases).
Malting barley for brewing
