Physicochemical characterisation of kafirins extracted from sorghum grain and dried distillers grain with solubles related to their biomaterial functionality

Abstract

Kafirins are hydrophobic prolamin storage proteins found in sorghum grain with properties that make them attractive for food-grade biomaterial applications, including use in drug delivery matrices and edible coatings. This study examined the physicochemical properties of kafirins extracted from two sources: directly from sorghum grain and from dried distillers grain with solubles (DDGS), a protein-enriched by-product of bioethanol production that undergoes high-temperature processing.

Kafirins from both sources were characterised using sodium-dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infra-red spectroscopy (FTIR), x-ray diffraction, small-angle x-ray scattering, scanning electron microscopy, and energy dispersive x-ray spectroscopy. DDGS kafirin demonstrated a very similar polypeptide profile to grain kafirin but exhibited an altered secondary structure with increased β-sheet levels compared to grain-derived kafirin. Surface analysis revealed fractals and elemental composition suggestive of enhanced reactivity and potential interfacial wettability in the DDGS-derived protein. These properties suggest DDGS kafirin possesses unique functionality that could enable its use as a novel food-grade biomaterial, potentially unlocking significant commercial value from what is currently considered a waste stream in bioethanol production.

@article{shah2021physicochemical,
  title         = {Physicochemical characterisation of kafirins extracted from sorghum grain
                  and dried distillers grain with solubles related to their biomaterial
                  functionality},
  author        = {Shah, Umar and Dwivedi, Deepak and Hackett, Mark and Al-Salami, Hani and Utikar,
                  Ranjeet P and Blanchard, Chris and Gani, Adil and Rowles, Matthew R and Johnson,
                  Stuart K},
  year          = 2021,
  journal       = {Scientific Reports},
  publisher     = {Nature Publishing Group UK London},
  volume        = 11,
  number        = 1,
  pages         = 15204,
  doi           = {10.1038/s41598-021-94718-z}
}