Ultrasound‐assisted fractionation of dried distillers' grains with solubles (DDGS) at mild temperature for co‐production of xylan and protein feed

Abstract

BACKGROUND: Ultrasound-assisted fractionation of DDGS under mild conditions was proposed for extracting xylan from dried distillers' grains with solubles (DDGS) and recovering protein-rich DDGS residue as animal feed. The composition and properties of xylan fractions and the DDGS residue obtained by ultrasound-assisted extraction and those by a conventional method of alkaline extraction without ultrasound-assistance were compared. RESULTS: Compared with the result for the conventional method, a similar xylan yield of 73.8% in the extracted liquid, but higher protein content of 26.2% in the DDGS residue were obtained by the ultrasound-assisted process with NaOH at ultrasound power of 900W and 30 ∘ C for 20 min. The ultrasound-assisted process has a significant impact on the sugar composition and polysaccharide side chain and polymerization degree of the xylan fractions. The DDGS residue produced by the ultrasound-assisted process had a fine porous structure as well as greater protein and essential amino acid content. The enzymatic hydrolysis of cellulose in DDGS residue reached 70% in the initial 3 h. CONCLUSION: Ultrasound-assisted fractionation was an efficient process for comprehensive utilization of xylan and protein in the DDGS. The xylan fractions with lower polymerization degree were perfect feedstock for xylooligosaccharide production by enzymatic hydrolysis. The DDGS residue with adequate nutrition composition and efficient digestibility had potential advantages as an alternative animal feed to DDGS.

A novel sub-pilot-scale direct-contact ultrasonic dehydration technology for sustainable production of distillers dried grains (DDG)

“…This could be part of the reason why ultrasonic drying has achieved a significantly higher drying rate and shorter drying time compared to HA. The fine holes on the surface as a result of the mechanical action of ultrasound are in line with the observations reported by Gu et al [66] on DDG residue. The exact reason for the formation of tiny holes on DDG surface is not known.…”

Proteins in dried distillers' grains with solubles: A review of animal feed value and potential non‐food uses

“…The combination of sieving and winnowing effectively shifted the composition of maize‐DDGS, particularly for larger particle classes (Liu, 2009). Gu et al (2019) compared NaOH treatment coupled with ultrasound with NaOH treatment for DDGS fractionation and showed that the former exhibited higher protein and essential AA contents in the DDGS extracts. Although physical treatments can separate DDGS into various size categories and elutriate different nutritional fractions, the purity and recovery of extracted proteins were relatively limited.…”

“…The conventional method of alkaline pretreatment increased the enzymatic hydrolysis of cellulose with 79% protein extraction efficiency (Zaini et al, 2019). Compared with individual NaOH pretreatment, the ultrasound‐assisted process with NaOH resulted in more significant protein and essential AA contents in the extract (Gu et al, 2019). Additionally, prolamin extraction from wheat‐DDGS was also conducted using an alkaline‐ethanol solution in the presence of reducing agents (Chatzifragkou et al, 2016).…”

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

“…Efficient techniques for extraction and concentration of this major protein from sorghum grain have been reported along with its techno-functionality for use as a “green” polymer to replace synthetic ones 4 . Similarly the extraction of kafirin from sorghum DDGS has received some research attention but fundamental understanding of its physico-chemical properties related to biomaterial techno-functionality is still lacking 5 , 6 .…”