Structural, physicochemical and interfacial stabilisation properties of ultrafiltered African yam bean (Sphenostylis stenocarpa) protein isolate compared with those of isoelectric protein isolate

Abstract Structural, Physicochemical and functional properties of ultrafiltered/diafiltered African yam bean (AYB) protein isolate (AYB UD ) were determined. These were also compared with isoelectrically precipitated AYB protein isolate (AYB ISO ). Both AYB UD and AYB ISO had the same X-ray diffraction (XRD peaks at 8.5° and 19.5°. The XRD profile for both AYB ISO and AYB UD showed partial crystalinity. Emission maximum ( λ max ) of the intrinsic fluorescence spectra associated with tryptophan (Trp) residue in both AYB UD andAYB ISO was observed at 330 nm, indicating a Trp residue that was deeply buried in hydrophobic core. Circular dichroism (CD) spectra showed that there were more highly ordered structure of α-helix, β and β-turns in AYB ISO than AYB UD . The surface hydrophobicity (H o ), emulsifying and foaming abilities of AYB ISO were significantly ( p  =  0.05 ) higher than those of AYB UD .