aleurone layer The single layer of large cells under the bran coat and outside the endosperm of cereal grains. About 3% of the weight of the grain, and rich in protein, as well as containing about 20% of the vitamin B1, 30% of the vitamin B2 and 50% of the niacin of the grain. Botanically the aleurone layer is part of the endosperm, but in milling it remains attached to the inner layer of the bran. See also flour, extraction rate.

aleurone layer A layer of cells below the testa of some seeds (e.g. barley), which contains hydrolytic enzymes (including amylases and proteases) for the digestion of the food stored in the endosperm. The production of enzymes is activated by gibberellins when the seed is soaked in water prior to germination.

aleurone layer The outer layer of living cells of the endosperm of wheat and other grain species. It is a single layer of cells that synthesizes the enzyme α-amylase, which is secreted during germination into the starch-filled endosperm and breaks down the starch into maltose and glucose. Studies on the barley grain have shown that gibberellins control the synthesis of the enzyme by switching on the genes for the synthesis of the specific RNA that codes for the α-amylase protein.