Optimizing the Supercritical Fluid Extraction of Lutein from Corn Gluten Meal

Supercritical CO2 was used to extract xanthophylls from corn gluten meal (CGM). Data from a Box-Behnken experimental design was used to model optimal lutein extraction based on extraction temperature (40–80 °C), pressure (5500–7500 psi), and fraction of ethanol co-solvent added (5–15% by volume of total solvent). Lutein extraction was also strongly correlated with zeaxanthin extraction with a correlation coefficient (r) of 0.995. The response surface model for lutein extraction indicated that the amount of co-solvent had the largest impact (p < 0.001) on lutein extraction yield. Influence of temperature and pressure were limited to quadratic or interaction effects (p < 0.15). The optimal lutein extraction conditions predicted with the model were a temperature of 40 °C, pressure of 6820 psi, and co-solvent (ethanol) addition of 15% by volume. At these conditions, lutein recovery from CGM was 2.6 times higher than the amount recovered with a quintuple extraction using ethanol and chloroform/dichloromethane (2:1). The strong linear effect of co-solvent addition suggests the possibility of further increasing lutein extraction with the addition of more co-solvent. CGM protein loss during extraction was also calculated and determined to be negligible.