Extração de proteínas e compostos fenólicos do resíduo do processamento de óleo de milho

Abstract

The residue obtained by the corn oil processing, composed of germ with defatted pericarp, has in its composition proteins, phenolics and fibers. Besides studies involving their use for animal feed, these residues have importance related to bioactive compounds present in residues from plant sources, thus, this work aimed to evaluate extraction processes of total phenolic compounds and proteins present in this residue using solvent extraction. The sample went through two types of drying processes: in a vacuum oven (60°C) and lyophilization. Solid-liquid extractions were performed using deep eutectic solvents formed by glycerol and choline chloride (ChCl: Gly); and by glycerol and sodium acetate (Ac: Gly) at 1: 1 and 1: 2 molar ratios, which were compared with aqueous alkaline ethanol solutions (EA) (50 and 65% v / v) using the solid / liquid fraction of 1:15 (m / v) at 50 ° C for 2 hours. After this procedure, quantification of total phenolic compounds by the Folin-Ciocalteu method and proteins by the BCA method of the extracts were performed. For protein extractions ChCl:Gly solvent using lyophilized sample presented better performance than Ac:Gly solvent extractions, resulting in extractions of 8.01±0.51 g/100g ROM and 5.42±0.14 g/100g ROM respectively. Only the molar ratio influenced the extractions with Ac:Gly, where the highest result was obtained for the molar ratio (1:2). Protein measurements of ethanolic extracts resulted in incoherent values, possibly by the extraction of other components from the sample that interfered in the analyzes. For the extraction of phenolic compounds, the eutectic solvents with higher molar fractions of glycerol presented better results and were similar to those obtained with alkaline ethanol 65%. It was obtained 33.34±2.61 mg EAG/g ROM for ChCl:Gly (1:2), 33.90±2.25 mg EAG/g ROM for Ac:Gly (1:2) and 29, 55±9.13 mg EAG/g ROM for EA 65%. The study showed that it is possible to extract and recover value-added compounds from the corn oil production residue using deep eutectic solvents and alkaline ethanolic solution.