Optimization of arachin extraction from defatted peanut (Arachis hypogaea) cakes and effects of ultra-high pressure (UHP) treatment on physiochemical properties of arachin

•Optimized process for extraction of arachin from peanut cakes was obtained by RSM.•The yield of arachin could reach 310.4 g/kg defatted peanut cakes.•The solubility and emulsifying property of arachin were improved by UHP.•Surface hydrophobicity and free sulphydryl groups of arachin were affected by UHP.

A process for the optimization of arachin from defatted peanut cakes had been developed. The process included pre-treatment, extraction by Tris–HCl buffer solution, pH adjustment and final separation by centrifugation. A Box–Behnken design including independent variables such as extraction temperature (x1), extraction pH (x2) and liquid–solid ratio (x3) was used. The variable with the largest effect was extraction pH. The optimum extraction conditions were found to be extraction temperature 56.0 °C, extraction pH 8.7 and liquid–solid ratio 14:1, under which the arachin yield could reach 310.4 g/kg defatted peanut cakes. The effect of ultra-high pressure treatment on the physiochemical properties of arachin was also evaluated. After processing, solubility, emulsifying activity, emulsifying stability and surface hydrophobicity changed significantly. The content of free sulphydryl groups, which were often associated with aggregation and gelation of proteins, also decreased. All the processes widened the utilization of by-products generated from oil extraction as a source of protein in human diet.