Salt-assisted aqueous extraction combined with Span 20 allow the obtaining of a high-quality and yield walnut oil

Abstract

To develop an effective and eco-friendly technique for walnut oil extraction, surfactant and salt-aided aqueous extraction (SSAE) method was used to break the emulsion. The optimal extraction parameters obtained by single-factor experiments (i.e., extraction time, 60min; extraction temperature, 85 °C; concentration of sodium chloride solution, 1.2 mol/L; liquid-to-material ratio, 5:1; concentration of Span 20, 1.7 g/100 g). The new aqueous extraction processing (AEP) procedure that was finally developed in this study recovered 91.2% walnut oil with high quality. Span 20 is effective in destabilizing the emulsions and improving oil recovery, which may be due to the fact that Span 20 could effectively replace the position of the oleosin to destabilize the emulsion. In addition, walnut protein has not been denatured after extraction of walnut oil by SSAE and can be reclaimed. Therefore, the discovery of Span 20 as an available demulsifier provides a new insight into the development of AEP of walnut.