Nebraska researcher Yiqi Yang is using the byproducts of sorghum as a colorant for textiles. The Charles Bessey Professor of biological systems engineering and of textiles, merchandising and fashion design is using wool to start his research, but hopes that in the future sorghum can be used on other textiles & throughout many industries.
After using the sorghum starch for industrial applications, the coproducts and byproducts that remain are called distillers grains. Distillers grains from corn digests easier than sorghum, so Yang's research looks to add a better value application for the sorghum industry for Nebraska. Yang and a group of Ph.D. students are currently working to see if the higher cross-linked proteins can have industrial applications, such as food-packaging materials or fibers for textiles.
A unique part of the research involves the sorghum husks. The husks contain a dark natural colour that can be used as a colorant. "If one could use it as a colorant for textiles, we're talking about a huge demand," Yang said. "This research is helping more than just the textile industry. By finding additional uses for co-products and byproducts we're adding value for farmers."
The team started out by dyeing wool because it can carry positive charges, which creates a better dye sorption since natural colorants generally carry negative charges and because the value addition is high. Yang believes that silks and nylons also have the potential to dye well.
While the hope is to eventually use the natural colorant from the sorghum husks to dye all types of textiles, cotton has been put on the backburner. Yang explains that there isn't enough of a value increase to cotton to encourage consumers to purchase a naturally dyed textile, because cotton is already a cheap material, and because natural cellulosics do not carry positive charges.
"You add more value to these highly valuable materials than cotton," says Yang. "If you work on the more valuable materials, the value addition is higher. Later, if the technology matures and the cost decreases, then of course we can work with other materials."
Once available, this natural colorant could reach a large market of consumers and brands. The project started with textiles and they have found some unique properties that make the product even more useful in other industries. Yang and his team are collaborating with researchers from Jiangnan University in China on this project.