Demulsification of peanut emulsion by aqueous enzymatic extraction using a combination of oleic and citric acids

Abstract

In the present study, the effect of demulsification of peanut emulsion using a combination of oleic and citric acids mechanism was investigated. The free oil yield was 95.87% under optimal conditions. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed that the protein composition of the emulsion treated with citric acid and oleic acid was similar to that of the sample emulsion. Citric acid increased the particle size and ζ-potential of the emulsion. When the content of oleic acid reached 1.5%, the conductivity of the emulsion significantly decreased and Fourier-transform infrared spectroscopy demonstrated that the intensity of the hydroxyl absorption peak decreased significantly. Gas chromatography analysis revealed that the content of free oil oleic acid increased by only 0.4–0.5%. The phase transformation process during demulsification was investigated by optical and confocal laser scanning microscopy. Oleic acid combined with phospholipids changed the surface hydrophilic–lipophilic balance, and the emulsion changed from oil-in-water to water-in-oil. Small-Angle X-ray scattering analysis deduced that the droplets in the demulsified emulsion were approximately spherical reverse micelles. Results from this study suggest that improvement of combination of oleic and citric acids technology to is important for the large-scale industrial application of an aqueous enzymatic method.