BACKGROUNDRecovering high value-added substances (oil, zein and carotenoids) from corn distillers dried grains with solubles (DDGS), the major coproduct of bioethanol, is important to enhance the profit of the corn ethanol process. Currently, few studies have been reported on separating high value-added substances in a process suitable for industrialization. In this article, a semi-continuous countercurrent extraction method was investigated to refine the corn DDGS. RESULTSFirst, an oil yield as high as 94.5% (based on oil content in DDGS) was measured using a series of five packed columns. Second, the DDGS residues after oil extraction were used for zein extraction, obtaining a zein yield of 24.5% (based on protein content in DDGS) with a series of four packed columns. Moreover, the carotenoids in zein were extracted by anhydrous ethanol in a Soxhlet apparatus. The extractives, which accounted for 17% of the original mass of zein, had a carotenoids content of 2.4 mg g(-1). Finally, zein was decolored by hydrogen peroxide to form a whiter product. CONCLUSIONSThe semi-continuous countercurrent method was developed successfully to refine the corn DDGS. The corn oil with high acid value was a perfect feedstock for biodiesel. The zein obtained achieved the quality of a commercial product. (c) 2015 Society of Chemical Industry