Comparison of prolamins from different cereals based on structure and functionality

In this study, the structure and functional properties of prolamins extracted from sorghum, rye, oat, barley and amaranth was systematic compared with commercial zein, e.g. secondary structure, electrophoresis profiles, sulfhydryl and disulfide content, surface hydrophobicity, emulsifying property and thermal stability. Kafirin and amaranth prolamin (AP) possessed much more ordered secondary structure. The conformation of hordein was more unfolded than other prolamins. Commercial zein possessed more tryptophan residues, while stronger polarity was observed in secalin, AP and avenin. As for the functionality, better emulsion activity and stability was found in avanin. Kafirin had the lowest denaturation temperature but highest enthalpy, which may be due to its lowest amount of β-turn and random coil. Stronger hydrophobicity was found with kafirin and AP, which was a positive correlation with oil holding capacity and emulsifying properties based on the principal component analysis. The findings provide some theoretical foundation in selecting desired prolamin to achieve more appropriate functional application.