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Isolation and Characterization of High-Purity Starch Isolates from Regular, Waxy, and High-Amylose Hulless Barley Grains

¹Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada. ²Corresponding author. Phone: 780-492-2898. Fax: 780-492-8914. E-mail: tv3@ualberta.ca ³Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.

Recovering starch from barley is problematic typically due to interference from β-glucan (the soluble fiber component), which becomes highly viscous in aqueous solution. Dry fractionation techniques tend to be inefficient and often result in low yields. Recently, a protocol was developed in our laboratory for recovering β-glucan from barley in which sieving whole barley flour in a semiaqueous (50% ethanol) medium allowed separation of the starch and fiber fractions without activating the viscosity of the β-glucan. In this report, we investigate an aqueous method which further purifies the crude starch component recovered from this process. Six hulless barley (HB) cultivars representing two each of waxy, regular, and high-amylose cultivars were fractionated into primarily starch, fiber, and protein components. Starch isolates primarily had large granules with high purity (>98%) and yield range was 22–39% (flour dry weight basis). More importantly, the β-glucan extraction efficiency was 77–90%, meaning that it was well separated from the starch component during processing. Physicochemical evaluation of the starch isolates, which were mainly composed of large granules, showed properties that are typical of the barley genotypes.