title: Molecular weight and structure of water soluble (1→3), (1→4)-β-glucans affect pasting properties of oat flours.
abstract: Seven experimental oat lines with high (5.9% to 7.2%), medium (5.3% to 5.5%), and low (4.4%) β-glucan concentrations were evaluated for the effects of β-glucan molecular weight (MW) and structure on viscosities of oat-flour slurries. The MW of β-glucans was determined by size-exclusion high-performance liquid chromatography. The structural features of β-glucans were measured by using fluorophore-assisted capillary-electrophoresis after complete hydrolysis with lichenase. The oat-slurry viscosities were measured on a Rapid Visco Analyser under 4 conditions: (1) without starch (amylolysis, removal of starch by α-amylase); (2) without β-glucan (removal of β-glucan by lichenase); (3) natural action of enzymes (autolysis, in sodium buffer); and (4) inhibition of enzymes (in silver nitrate solution). Excluding one line (regression outlier), significant correlations (P < 0.05) between peak MW of β-glucan and viscosities of oat slurries were obtained under inhibition. The ratio of degree of polymerization (DP) 3/DP4 negatively correlated with viscosity under amylolysis, autolysis, and inhibition (P < 0.05). The amount of DP ≥ 5 negatively correlated with pasting final viscosity after β-glucan removal by lichenase (P < 0.05). Positive correlations (P < 0.05) between the ratio of β-(1→4)/β-(1→3) linkages and viscosities under autolysis and inhibition were found. Overall, these findings demonstrated that the peak MW, ratio of DP3/DP4, amount of DP ≥ 5, and ratio of β-(1→4)/β-(1→3) linkages of β-glucans impacted pasting properties of oat-flour slurries.
authors.affiliation: Dept. of Food Science and Human Nutrition, Iowa State Univ., Ames, IA 50011, USA.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Liu
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: White
mesh_terms: D018554:Avena / Q000737:chemistry* / Q000235:genetics; D002236:Carbohydrate Conformation; D055598:Chemical Phenomena; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004043:Dietary Fiber / Q000032:analysis* / Q000378:metabolism; D019075:Electrophoresis, Capillary; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005433:Flour / Q000032:analysis*; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D055595:Mechanical Phenomena; D008970:Molecular Weight; D012639:Seeds / Q000737:chemistry*; D012995:Solubility; D013045:Species Specificity; D014783:Viscosity; D047071:beta-Glucans / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004043:Dietary Fiber; D004791:Enzyme Inhibitors; D047071:beta-Glucans; C067858:beta-glucan, (1-3)(1-4)-; D006026:Glycoside Hydrolases; C028020:licheninase