Separation of high-value products from ethanol extracts of corn by chromatography

This research details the development of a new one-step process for producing high-value products such as zein and xanthophylls from corn to enhance the economic viability of the dry-grind ethanol industry. This process was designed for incorporation in a dry-grind ethanol plant, and thus in-house ethanol was the processing solvent for the entire processing chain, from the initial extraction of the whole ground corn to the final purification steps. Dry-ground whole corn was extracted with 70% (v/v) ethanol and filtered. The extract was processed by preparative-scale size exclusion chromatography with aqueous ethanol as the mobile phase and an ethanol-stable resin as the stationary phase. The largest component (zein) was totally excluded in the void volume of the column while the impurities and the xanthophylls interacted with or passed through the pores of the resin and separated according to their mobilities. Starting with 17 g of corn or 50 mL corn extract, one can obtain about 320 mg of zein with 90+% yield and purity in this method. Thus, a typical dry-grind ethanol plant processing 50 million gallons of ethanol per year, can produce about 13 million kg of zein and 7.5 tonnes of xanthophylls and this implies an additional revenue of $95million (conservative valuation: zein ∼$4.4 kg−1 and xanthophylls ∼$5 g−1) without bringing in any additional raw materials. This is about 1.5–2 times the present revenues of such an operation.