Oil and protein recovery from corn germ: extraction yield, composition and protein functionality

Abstract This work aimed the recovery of oil and protein fractions from corn germ (CG) generated as a by-product during flour processing. Several oil extraction techniques were investigated: hexane at room temperature, hexane at 45 °C, supercritical carbon dioxide (Sc-CO2) and Soxhlet with hexane and ethanol. Their influence on oil yield and oil composition as well as on the further protein extraction was assessed. Proteins extracted from the various meals were characterized for their protein content (19.9-48.5%), their water absorption capacity (WAC 1.34-2.79 g water/g), solubility profile, and foaming (FC 25-84%) and emulsifying (EAI 84.8-246 m²/g protein) capacities. The fatty acid profile of the oil was the same regardless the extraction method. Though yielding partial defatting (16.4 vs 23.8 g oil/100 g CG), Sc-CO2 produced oil with high phenolic content (251.8 mg GAE/kg oil) and high-quality CG meal concurrently. The protein extract produced from this partially defatted meal showed interesting characteristics such as the highest protein concentration (48.5%), the highest foaming properties (FC and FS > 84%), high WAC (2.33 g water/g extract) and EAI (231 m²/g). Defatting conditions, namely the solvent nature, temperature and pressure, influenced the functional properties of further extracted proteins by inducing changes in their conformational state.