Influence of Enzyme Distribution on Endosperm Breakdown (Modification) During Malting

The development of endosperm-degrading enzymes and their patterns of release from the aleurone to the starchy endosperm were studied in mainly Klages barley. Enzyme development in the scutellum of the embryo was associated with aleurone contamination. The aleurone layers of excised endosperms produced α-amylase in the absence of growing embryos, suggesting that aleurone-free scutellar tissue of barley does not have the potential to synthesize and secrete significant levels of endosperm-degrading enzymes into the starchy endosperm of germinated barley. Spray steeping, in contrast to multiple steeping, reduced endosperm breakdown and increased β-D-glucan release and extract viscosity. Spray steeping also depressed the development of α-amylase, endo-β-1,3:1,4-glucanase, and pentosanase but encouraged development of endo-β-1,3-glucanase. Gibberellic acid was essential for optimal enzyme development and release. Even in the presence of gibberellic acid, however, a significant quantity of pentosanase was retained in the aleurone. Although spray steeping depressed the malting potential of Klages, preliminary studies showed that it encouraged the malting performances of Conquest and Bonanza barleys. Steeping methods determine malt quality by promoting optimal enzyme development and secretion into, and uniform hydration of, the starchy endosperm.