Dietary fibers are often co-consumed with phenolic rich foods or beverages and the impact of their molecular interactions on the polyphenols' biochemical properties have been thoroughly investigated. However, the impact of these interactions on the physico-chemical properties of the dietary fibers received little attention, although these physico-chemical properties are critical to the nutritional properties of the fibers. In this study, we report the characterization of oat β-glucans binding with phenolic compounds by Isothermal Titration Calorimetry and the impact on this binding on the rheological properties of β-glucans gels and oat bran throughout in vitro digestion. Binding between phenolic compounds and β-glucans has been shown to be spontaneous (ΔG〈 0 J), quantitative but reversible (Ka 〉103 mol/L), non covalent (ΔH〈 50 kJ/mol), primarily driven by hydrogen bonding for simple phenolic acids with a significant contribution of hydrophobic interactions (ΔS 〉0 J/mol.K) for catechins. In presence of phenolic compounds, the viscosity and stress of β-glucan gels were decreased at all shear rates (10-1-103 s-1). The magnitude of this decrease was shown to be dose-dependent and phenolic compound-dependent, more binding leading to further decreased viscosity. Similar effects were observed on oat bran throuhgout in vitro digestion, where oat bran in presence of phenolic compounds exhibited viscosities lower than that of oat bran alone by up to 30% . This work shows that phenolic compounds associated with oats β-glucans can impact the β-glucans' physical and nutritional properties, therefore impact potential health claims associated with the β-glucans.

Non covalent binding of phenolic acids with oat β-glucans: impact on the physico-chemical properties of β-glucans

2019 Spring National Meeting

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