Optimization of extraction process of protein from Metaplexis Japonica Makino nutshell and evaluation of its antioxidative activity

The theory of alkali extraction and acid precipitation was employed to optimize the extraction conditions of protein from Metastasis Japonica Makino nutshell ( MJNP) , and protein extraction rate as index, by means of the single factor experiments and orthogonal experiment.The results showed that the optimum conditions were as follows: ratio of solid to liquid of1∶ 20 ( g/m L) , solution p H11.5, temperature of 60 ℃ and extraction time of 1.0 h, and the average extraction yield was 89.18%.Antioxidant experiments were primarily evaluated, under the condition of the optimized process, the protein had the scavenging capacity against DPPH· and ·OH with the scavenging rate of 79.45% ( 8 mg/m L) and 55.35% ( 8 mg/m L) , the IC50 value of DPPH·, and ·OH was 4.19 mg/m L and 3.30 mg/m L, respectively. Moreover, the protein extracted from Metastasis Japonica Makino nutshell possessed weaker reducing power than VC.