Two fraction extraction of α-zein from DDGS and its characterization

Zein was recovered from corn distiller's dried grains with solubles (DDGS) by a modified method using 70% (w/w) aqueous 2-propanol (70-IPA) or 70% (v/v) aqueous ethanol (70-EtOH) solvents, and a commercial method using 88% (w/w) aqueous 2-propanol (88-IPA). Yield, purity, and film properties of the isolated zein were determined. The modified procedure extracted two fractions of zeins: a mostly α-zein fraction, and a mostly γ-zein fraction. The modified method increased α-zein yield from 4% to 14%. Enzyme cellulase pretreatment did not improve zein yield, but grinding did. The α-zein fraction showed electrophoretic bands at 40, 22, 19, and 10 kDa, corresponding to α-zein dimer, α1-zein, α2-zein, and δ-zein, respectively. The α-zein of DDGS retained its film forming capability. The α-zein film of unmodified DDGS was cloudy and rough, unlike the clear and smooth films of α-zeins isolated from corn gluten meal and enzyme-treated DDGS.

► Functional zein proteins were recovered from corn fermentation coproduct, DDGS.
► Recovery and functional characteristics of the isolated zein were determined.
► Recovering functional zein from DDGS will add value to grain based fuel ethanol industry.
► The isolated α-zein of DDGS retained its film forming functional properties.
► DDGS zeins could have potential applications in industrial biobased products.