Non-Carbohydrate Components on the Surface of Starch Granules According to the Hardness of Wheat

Abstract

An attempt was made to demonstrate the usefulness of pre-knowledge of the quality and quantity analysis of non-carbohydrate components of starch surface, such as proteins and lipids, in starch isolated from wheat with varying degrees of hardness, for receiving glucose hydrolysates. The chemical composition of starches isolated from wheat grains of different hardness was examined. The amount of protein fraction (surface proteins, puroindolins and internal proteins), total and surface lipids, apparent amylose, phosphorous and pentosans contents were evaluated. It was found that starches, depending on the hardness of wheat grain, have a different chemical composition. A clear influence of wheat hardness on lipid and proteins content on the surface of starch grains and on apparent amylose was proved. It was showed that the presence of polar lipids (glyco and phospholipids) on the surface of starch was connected with their role in binding of surface proteins fraction (friabilins) to starch grains. There was a clear positive correlation between the amount of lipid fraction on starch surface and the amount of protein fraction, depending on wheat hardness. Starches from soft wheat varieties were characterized by higher amounts of proteins and lipids on their surface. In addition, it was determined that basing on the knowledge of mechanical properties of wheat grains, namely its hardness and initial starch chemical content analysis, one may predict its further directions of processing, including evaluation, whether the starch from a given wheat variety would be appropriate for obtaining hydrolysates with good physicochemical properties.