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Regenerated Sorghum Proteins from Distillers Grains for Industrial Applications

Wei Li, University of Nebraska - Lincoln


Sorghums have become especially important in arid regions due to their drought and heat tolerant nature. The annual production of sorghums reached 14.6 million metric tons in the United States, making sorghums important industrial crops. Due to the high demand for ethanol production, over 450 kilotons of sorghum distillers grains were produced annually and mainly used as animal feed. However, sorghums are unpalatable to humans and live stocks due to their poor digestibility, and thus supplied at limited demands as foods. New industrial applications of sorghum crops and distillers grains are needed. Proteins, accounting for 7-15% of sorghum grains and 30-40% of distillers grains, are expected to possess better tensile properties and aqueous stabilities than common proteins due to their high crosslinking degrees, and thus become a promising candidate to replace the unsustainable petroleum products. However, difficulties occur in sorghum protein extraction and processing because they extensively cross-link to a greater degree than similar plant proteins like zein. Extraction of sorghum proteins with high efficiency and quality for satisfactory properties of end products still has not been achieved with previous methods. In this research, a green urea-cysteine based system was developed to extract sorghum proteins with preserved backbones, linear structures and sufficient thiol groups for re-oxidation at high efficiency. Quantified effects of preservation of backbones and recovery of disulfide bonds on tensile strength were investigated. Sorghum protein films from the urea-cysteine based system have their crystallinity, tensile properties and water-vapor-barrier properties 21%, 27% and 28%, respectively, higher than those from the conventional ethanol based system. The extract sorghum proteins were made into bio-composites, nanoparticles and films for various applications. The effect of hydrolysis time on the structure and properties of different cellulose nanowhiskers and their reinforcing effects on the sorghum protein based bio-composites were studied. Loading efficiencies of eugenol to sorghum protein nanoparticles and durability of eugenol loaded in sorghum protein nanoparticles in cotton were investigated. Ability of plasticizers to stretch sorghum protein molecules was demonstrated by rheology, circular dichroism and particle size analyses. The proposed mechanism of plasticizer migration in protein matrix was verify by the change of tensile properties of films. A quantitative relationship between sorghum protein-plasticizer compatibility and ability of sorghum protein films to resist brittleness was established.

Subject Area

Textile Research|Materials science|Nanotechnology|Food Science|Toxicology

Recommended Citation

Li, Wei, "Regenerated Sorghum Proteins from Distillers Grains for Industrial Applications" (2019). ETD collection for University of Nebraska - Lincoln. AAI22592370.