Study On Extraction Technology Of Polyphenols From Longan Pericarp And Its Antioxidant Properties

The extraction process of polyphenols from Longan pericarp was studied, and the extract of polyphenols was evaluated as antioxidants. The results showed as follows:(1)Polyphenols were extracted with organic solvents, and were investigated by single factor and orthogonal design. The optimum extraction conditions were concluded that: ethanol concentration of 70% , solid-to-liquid ratio of 1∶5 (g:mL), extraction time of 1 h, 50% acetone-water solution, temperature of 50℃. The ratio of polyphenols content was 2.71% under these extracting conditions.(2)The static absorption capacity of the crude extract was used to investigate different macroporous resin, results showed that the macroporous resin of HPD-826 was the best static absorbent; The best purify process conditions were determined by the static and dynamic absorptive and desorptive performance: the sample solutions( pH value of 5.0 , concentration of 8 mg/mL, current velocity of 2 BV/h ) was passed through HPD-826 resin , and the eluant 70% ethanol and eluant volume of 2 BV/h after saturated absorption. The ratio of polyphenols content was 2.1%.(3)The antioxidation test in vitro indicated that the extraction of polyphenols from Longan pericarp exhibited high free radical scavenging activity, IC₅₀=0.13 mg/mL, which higher than that of V_c (IC₅₀=0.27 mg/mL); but its effects of scavenging O^2- free radical was not as good as V_c . It has more significantly reducing capacity than V_c . The results also showed that the extraction of polyphenols was more effectively in slowing down the rate of oxidation of oil than V_E. polyphenols from Longan pericarp was a kind of potential natural antioxidant.