Structural Differences in the Mature Endosperms of Good and Poor Malting Barley Cultivars

Scanning electron microscopy (SEM) was used to examine a number of good and poor malting quality barley cultivars of both spring- and winter-sown type. Mature grains were frozen and fractured, and the endosperm surfaces were examined, with particular attention given to the sub-aleurone and starchy endosperm regions. All of the cultivars showed similar patterns of endosperm cell size, distribution and packing. However, variation in the patterns of fracture through the endosperm, and in the extent of starch–protein adhesion, were observed. Poor malting quality cultivars had fracture planes that traversed the starch granule—protein matrix interface, indicating a high degree of starch–protein association similar to that exhibited by hard wheat cultivars. In contrast, good malting quality cultivars had fracture planes around the starch granules, indicating a low degree of starch–protein binding similar to that exhibited by soft wheat cultivars. The possible role of starch–protein binding in malting performance is discussed.