Extraction process optimization of L. meyenii polyphenols by response surface methodology and analysis of its antioxidant activity

【Objective】In order to provide theoretical basis for rationally developing and utilizing Lepidium meyenii polyphenols, the extraction process conditions of L. meyenii polyphenols were optimized,and its antioxidant activity was analysed and determined. 【Method】Using L. meyenii root as experimental materials, the material-liquid ratio, extraction temperature and time were optimized to obtain optimal process conditions and establish regression model through response surface methodology, which were selected based on single factor tests. Meanwhile, the scavenging effect of L. meyenii polyphenols on hydroxyl radical(·OH), DPPH radical(DPPH·) and ABTS radical(ABTS+·) was determined. 【Result】The regression equation for extracting L. meyenii polyphenols was established by response surface methodology : Y=4. 59-0.036A+0.13B+0.039C- 0.037AB- 0.032AC- 7.25×10-3BC- 0.1A2- 0.25B2- 0.046C2(Y was extraction rate, A was material-liquid ratio, B was extraction temperature, C was extraction time, R2=0.989), which showed a good fitting degree.Therefore, the optimal process conditions were as follows: using water as extraction solvent, liquid-material ratio of 75 m L/g,extraction temperature of 82 ℃ and extraction time of 151 min. Under the above optimum conditions, the extraction rate of polyphenols reached up to 4. 630%, which approached to theoretical value( 4. 602 %). In addition, L. meyenii polyphenols had obvious scavenging effects on ·OH, DPPH· and ABTS+·, and the scavenging effects was increased with increasing mass concentration of polyphenols, the maximum scavenging rate were 76.4%, 91.3% and 87.4%, respectively.【Conclusion】The optimized extraction process parameters are accurate and reliable, which can be applied to the actual extraction process of L. meyenii polyphenols. Furthermore, L. meyenii polyphenols have strong antioxidant activity, thus which can be developed and utilized as resource of natural antioxidants.