Supercritical Carbon Dioxide Extraction of Corn Distiller’s Dried Grains with Solubles: Experiments and Mathematical Modeling

Abstract

Corn distiller's dried grains with solubles (DDGS) is a byproduct of the ethanol industry and has potential as a source of valuable compounds. In this study, corn DDGS was extracted using supercritical carbon dioxide (SC-CO(2)) at 50-70 °C, 34.5-49.6 MPa, and constant CO(2) flow rate of 1 L/min (measured at ambient conditions). The highest yield of total lipids (9.2%, w/w) was obtained at 49.6 MPa/70 °C. Apparent solubility of corn DDGS lipids ranged between 0.010 kg/kg CO(2) at 34.5 MPa/50 °C and 0.026 kg/kg CO(2) at 49.6 MPa/70 °C. The extract contained 107 mg/kg carotenoids, 1538 mg/kg tocochromanols, and 15904 mg/kg phytosterols at 49.6 MPa/70 °C. The Sovova model and Chrastil model were successfully used to describe the extraction of total lipids and apparent solubility of total and minor lipids, respectively. The study revealed that DDGS is a good inexpensive source of lipids and valuable minor lipid components and that SC-CO(2) extraction can be used as a "green" process to add value to corn DDGS by recovering such high-value lipids.