Physicochemical properties of small- and large-granule starches of waxy, regular, and high-amylose barleys

Small- and large-granule starches were isolated from pin-milled and air-classified fractions of waxy (SB 89528), regular (Condor), and high-amylose (Glacier) barleys, and their physicochemical properties were investigated. The isolations contained 95-97% starch, 0.1-0.3% protein, and 0.1-0.2% ash. Scanning electron microscopy showed that the starch granules were oval to round in shape with diameter ranges of 2-10 μm for small and 12-26 μm for large granules. The starches had A-type X-ray diffraction patterns, typical of cereal starches. The differences in the physicochemical properties such as X-ray diffraction relative intensities, swelling factor, amylose leaching, Brabender pasting, differential scanning calorimetry thermal characteristics, and resistance to acid and α-amylase hydrolysis were greater among the three genotypes than between the small- and large-granule starches from the same genotype. The large-granule barley starches may be substituted for corn starches because their physicochemical properties are generally similar.