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 %β‐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 β‐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 α‐amylase to eliminate the effect of starch; and 3) treated with lichenase to remove β‐glucan. The β‐glucan was extracted by a process involving multiple precipitation and dialysis steps, and the MW distributions were determined by HPLC. %β‐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 β‐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 β‐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 β‐glucan was associated with pasting properties after amylase hydrolysis, but not after treatment with lichenase or in SN solution.