RELATIONSHIP BETWEEN ACID EXTRACT VISCOSITY AND TOTAL SOLUBLE AND INSOLUBLE β-GLUCAN CONTENTS OF HULLED AND HULLESS BARLEY

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Abstract
The extent of variability in acid extract viscosity and its relationship to total soluble and insoluble β-glucan was determined in hulled (Bonanza) and hulless (Tupper and Scout) cultivars of barley grown at several locations on the Prairies. Acid extract viscosity was influenced significantly by cultivar, year and location in the Saskatchewan Agricultural Development Fund Regional Variety Test and by cultivar in the Hulless Barley-Wheat Comparison Test. The cultivar ranking for the 2-yr mean extract viscosity was Bonanza < Tupper < Scout. Total and soluble β-glucan were determined with an endo-β-glucanase purified from a crude bacterial α-amylase preparation (BAN 1000 S). Soluble β-glucan, on average, formed 32.7%, and the insoluble (calculated by difference) the remainder 67.3% of the total β-glucan content of barley. Acid extract viscosity was positively correlated (r2 = 0.83, n = 15) with total β-glucan content. The correlation between total and insoluble β-glucan content was + 0.68. Perchloric acid extraction of the meal followed by enzymatic hydrolysis of the extract was the most rapid and convenient procedure for the determination of total β-glucan content of barley.Key words: Barley (hulled, hulless), β-glucan, soluble β-glucan, insoluble β-glucan, acid extract viscosity