Molecular weight distribution of (1→3)(1→4)-β-Glucan affects pasting properties of flour from oat lines with high and typical amounts of β-glucan

Experimental (N979-5-2-4 and IA95111) and traditional oat lines (Jim and Paul) with average %beta-glucan of 7.5, 7.8, 4.9, and 4.4%, respectively, were grown in 2002, 2003, and 2004. Molecular weight (MW) distributions of the beta-glucans were examined for potential variations among growing years and for relationships with pasting properties measured by Rapid ViscoAnalyser under three separate conditions: 1) in silver nitrate (SN) solution to inactivate enzymes; 2) hydrolyzed by alpha-amylase to eliminate the effect of starch; and 3) treated with lichenase to remove beta-glucan. The beta-glucan was extracted by a process involving multiple precipitation and dialysis steps, and the MW distributions were determined by HPLC. %beta-Glucan in N979-5-2-4 and IA95111 lines were consistently and significantly greater (P < 0.05) than in Jim and Paul lines during three growing years. The contribution of P-glucan to peak viscosity on the RVA was substantially greater than that of the starch for all three years. The molecular number average and peak MW of beta-glucan from N979-5-2-4 and IA95111 were greater than these values for Jim and Paul, and values were consistent among years. The MW of extracted P-glucan was associated with pasting properties after amylase hydrolysis, but not after treatment with lichenase or in SN solution.