Recovery of acid corn oil from the bioalcohol industry by molecular distillation

Abstract

Background: The objective of this work was to reduce the acidity of acid corn oil for its subsequent use as edible oil. Also, its tocopherols composition was determined. This oil is obtained as a by-product of corn alcohol production on an industrial scale and is currently used as a raw material in the biodiesel industry.

Results: The tocopherols and fatty acids composition of acid corn oil was determined by gas chromatography, and molecular distillation experiments were carried out at different temperatures between 110 °C and 190 °C with a volumetric flow rate of 0.5 to 2 mL min^-1 and a pressure of 5 × 10^-5 atm. It was possible to reduce its acidity from 9.44% (as oleic acid) to values less than 0.3% in the residue, with distillation temperatures higher than 180 °C; also, in the distillate, the tocopherols were recovered with concentrations up to 13 360 ppm.

Conclusion: It was possible to decrease the acidity and purify tocopherols from acid corn oil by molecular distillation, obtaining a residue with an acidity acceptable for human consumption and a distillate with a high tocopherols content. Therefore, using molecular distillation, added value was given to a by-product of the bioalcohol industry. © 2019 Society of Chemical Industry.

Keywords: acid corn oil; free fatty acids; molecular distillation; tocopherols.