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.

Oat (<i>Avena sativa</i> L.): Oil and Nutriment Compounds Valorization for Potential Use in Industrial Applications

“…Several studies 101 103 identified that oat β-glucan content falls roughly within 2.5-8.3 of dry grain. In addition, β-glucan polydispersity 104 such as polymer molar masses distribution and polymerization degrees were interesting because the higher-molecular-weight components were highlighted to be biologically beneficial and effective. Report of Lazaridou and Biliaderis 105 proved the significance of the molecular weight of β-glucan polydispersity covering the range of 65-3100 kDa.…”

Effect of Heat Treatments on Starch Pasting, Particle Size, and Color of Whole‐Grain Barley

“…The starch-pasting profile of barley products depends on many factors, including cultivar and the amylose/amylopectin ratio (Yanagisawa et al 2006;Gujral et al 2013;Li et al 2014). Additionally, BG largely contributes to the viscosity and needs to be accounted for when analyzing wholegrain barley flour (Liu and White 2011). Typically, viscosity reduction in the starch-pasting profile of cereal grain products is attributed to partial starch gelatinization, which can occur during heat treatment.…”

Application of the Rapid Visco Analyzer (RVA) as an Effective Rheological Tool for Measurement of β‐Glucan Viscosity

“…The RVA has been employed for standard methods in cereal applications, including a method to measure pasting properties of oat flours (AACCI 2010). It was also used to study the effects of β-glucan molecular weight and structure on viscosities of oat flour slurries under different enzyme treatments (Liu and White 2011).…”