Steeping, the first of the three stages of the malting process. See malting. The aim of steeping is to take barley that has recovered from dormancy and has been stored at about 11% to 14% moisture and to raise the moisture content of the grain to around 43% to 47% by successive immersions in water over a period of approximately 2 days. See dormancy (of barley).

Modern malting procedure uses interrupted steeping—alternating periods of water immersion and dry periods known as air rests. During each of two or three (occasionally four) wet periods, the grain/water mixture is aerated to maintain aerobic conditions for the grain. In the intervening dry periods, air is drawn through the damp grain to remove the carbon dioxide produced by respiration of the barley seeds. This helps approximate the conditions in which the seeds would normally grow and therefore stimulates them to germinate.

Steeping normally proceeds in the temperature range of 15°C to 20°C (about 60°F to 70°F). It takes place in a purpose-designed vessel of either cylindroconical or flat-bottom design. The latter has a plenum area situated below slotted floor plates to permit even ventilation and aeration.

Water enters the grain primarily through the micropyle at the embryo end of the grain. Accordingly, hydration of the grain occurs from the proximal toward the distal end, and the moisture content of the embryo will be higher than that of the endosperm during wet phases until the grain equilibrates during subsequent dry phases. Increasing the grain moisture performs two main functions: it stimulates the embryo to start to grow and water penetrates the endosperm matrix, allowing enzymic activity to take place during the germination stage.

Rapid, even, and complete hydration allows successful germination to follow—steeping is the key stage in malting to allow satisfactory modification of the grain during the remainder of the process.

See also germination and modification.