EXTRACTION OF PROTEINS FROM CORN OIL PROCESSING RESIDUE USING DEEP EUTECTIC SOLVENTS

The growing interest in protein rich diets, combined with the increase in vegetarians and vegans, has led to the search for vegetable protein sources. In the processing of corn oil it is obtained a residue consisting of germ with defatted pericarp (COPR) that contains proteins of high nutritional value and technological potential. This makes COPR a protein source candidate for human diet. Thus, this study evaluated extraction processes of proteins from this residue using deep euthetic solvents (DES) and ethanol. Before extractions, COPR was dried in a vacuum drying oven (60°C) or by lyophilization. Extractions were performed using DES formed by choline chloride and glycerol (ChCl:Gly) or by sodium acetate and glycerol (Ac:Gly) at 1:1 and 1:2 molar ratios, which were compared with alkaline ethanol solutions (NaOH 1M) (EA) (50 and 65% v/v) using solid/liquid fraction of 1:15 (m/v) at 50 °C for 2 hours. Proteins in the residue were quantified by the Kjeldahl method and in the extracts by the BCA method, which were expressed in g of extracted proteins/100g residue. The total protein content of COPR was 8,05±0,05% (%w/w). Lyophilized residue provided higher extractions in the processes with ChCl:Gly and EA 50%. Only the molar ratio influenced the extractions with Ac:Gly, with the highest result obtained for molar ratio (1:2) (6,27±0,64). ChCl:Gly extractions using lyophilized residue showed better performances than extractions using Ac:Gly. They resulted in extractions of 8,01±0,51 (molar ratio 1:2) and 7,61±0,10 (molar ratio 1:1). Among the extractions with EA, only extraction with EA 50% and residue dried in a vacuum oven was different from the others and provided the lowest result (27,83±2,09). Protein measurements of the ethanolic extracts resulted in inconsistent values, possibly due to the presence of extracted interfering substances. The study showed that DES were able to extract proteins present in COPR.