THE INFLUENCE OF ENDOSPERM STRUCTURE ON THE BEHAVIOUR OF BARLEYS IN THE SEDIMENTATION TEST

Abstract

Detailed microscopic studies of the relationships between endosperm structures and sedimentation scores show that the sub-cellular organization of the endosperm of barley grains plays a greater part in influencing sedimentation scores than do levels of nitrogen and β-glucans. Differences in sedimentation scores of barleys are directly related to the number of large starch granules which are released from the protein matrix during the milling stage of the sedimentation test. The sedimentation scores of some barleys can be affected by the presence of grains which are visually mealy. The mealy grains selected from a particular sample of barley give higher sedimentation scores than the remaining vitreous grains. However, a high degree of mealiness would be required to cause a significant shift in the usual sedimentation score of a barley sample. The mealy and vitreous grains of the fast-malting barley, Proctor, give higher sedimentation scores than do corresponding grains from Julia, which malts more slowly. The overall structural arrangements of the endosperm cells of Proctor and Julia are similar and can therefore have little effect on the sedimentation scores of these barleys. The central and dorsal cells of the endosperm are smaller and more elongated than are the more laterally placed cheek cells. The latter types of cell thus have a higher ratio of starch to cell wall.