ISOLATION AND ANALYSIS OF STARCH FROM SINGLE KERNELS OF WHEAT AND BARLEY

A method for isolating granular starch from single kernels of wheat and barley is described. Whole kernels were degermed, cracked, steeped in water, then macerated to release crude starch which was purified in two stages. Centrifuging through 80% (w/v) caesium chloride removed all less dense cellular material, storage proteins and some starch granule surface proteins. For some purposes this starch was sufficiently pure, but normally all traces of surface proteins and lipids were removed by washing with 0·5 % sodium laurate. Starch preparations were washed several times with water, then acetone, and finally air-dried. Starch yields and properties using the single kernel (SK) method were similar to those of bulk starch prepared conventionally from 10–30 g grain. Granule dimensions of SK starch, measured by Coulter Counter, were slightly smaller but recoveries of small B-granules were frequently better. Gelatinization properties of SK starch, measured by differential scanning calorimetry, and carbohydrate composition were very similar to those of bulk starch, but lipid and protein contents were lower due to the more efficient removal of contaminants from the surface of the granules with caesium chloride and sodium laurate. © 1990, Academic Press Limited. All rights reserved.