Effects of the oat β-glucan on the functional and structural properties of defatted walnut meal flour

Abstract

The effects of oat β-glucan (OβG) with different concentrations (0–2.5%) on the functional and structural properties of walnut meal flour (WMF) were investigated. Fourier transform infrared (FTIR) analysis showed that the β-sheet content in WMF-OβG mixtures increased to 48.13%, while α-helix, random coil and β-turn decreased to 13.79%, 12.08% and 25.28%, respectively. Scanning electron microscopy (SEM) analysis exhibited that the surface structures of WMF and WMF-OβG mixtures were similar. Moreover, WMF-OβG mixtures presented a larger average particle size and a lower zeta-potential. Differential scanning calorimetry (DSC) result confirmed that the transition temperature of WMF-OβG mixtures was significantly higher than WFM, but the enthalpy was lower (p < 0.05). The rheological evaluation revealed that the OβG increased the storage modulus (G′), loss modulus (G′′) and viscosity of WMF. The WMF-OβG mixtures showed the higher foaming capacity, foaming stability and emulsion stability than that of WMF, while the emulsifying activity decreased. These findings suggest that OβG is an appropriate ingredient for modifying WMF functional properties, and can be potentially used in bakery, beverage and meat products.

Keywords

• Walnut meal flour
• Oat β-glucan
• Structure
• Rheological property
• Emulsifying property
• Foaming property