| Lotus seed (Nelumbo nucifera Gaertn) belongs to Basidiomycotina. It is a kind of precious fungus used for food and medicine, which has rich nutrition and special health value. The extraction technology, the anti-oxidantive effect and the antibacterial activity of lotus seed polyphenols were studied in this paper. And then the active components of lotus seed polyphenols were analyzed by HPLC. In order, an important recommedation for developing deep-processing products of lotus seed were offered.(1) The extraction technology of polyphenols from dried lotus seed was studied in this experiment. Different factors were considered, such as the kinds of the solvent, the concentration of solvent, extractive temperature, ratio of material to liquid, extractive time and extractive frequency. Based on the single factor tests, the optimum extraction technology was determined through orthogonal experiments: the ethanol concentration was 90%, the ratio of material to liquid was 1:15, the extraction time was 1.5 hours, the extractive temperature was 60℃, and the extractive frequency was 3 times. Under this condition, the extraction rate of lotus seed would be 7.58 mg/g. Ultrasonic effect on the extraction rate of lotus seed polyphenols were studied, in addition, the result shown ultrasonic effect could improve the extraction rate of lotus seed polyphenols.(2) The extraction of lotus seed polyphenols by microwave-assisted extraction technique were studied in this experiment. Different factors were considered, such as ethanol concentration, microwave power, treatment time, ratio of material to liquid, and so on. Based on the single factor tests, the optimum extraction technology was determined through orthogonal experiments: ethanol concentration was 90 %, ratio of material to liquid was 1:10, the power of the microwave radiation was 300 W, extraction time was 35 s, the frequency of microwave extraction was three times. Under such conditions, the extraction rate of lotus seed was 7.74 mg·g-1.(3) Using tea polyphenol(TP)and Vc as comparisons, the effect on scavenging·OH and·O2- of lotus seed polyphenols (LSP) was studied by using fenton reaction and pyrogallol autoxidation methods respectively. The results showed that lotus seed polyphenols had certain ability to scavenge·OH and·O2- with the various concentrations in the study. When the concentrations were same, lotus seed polyphenols have stronger ability to scavenge·O2- than tea polyphenol and Vc, but have weaker ability to scavenge·OH. The oil anti-oxidation of lotus seed polyphenols was studied, In addition, the result shown that lotus seed polyphenols have certain ability of anti-oxidation to oil.(4) Using tea polypheno(lTP)as the comparison, The antibacterial action of lotus seed polyphenols was studied. The result shown that lotus seed polyphenols have a notable inhibiting microorganism activity against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Bacillus subtilis and listeria spp, but it have no antibacterial activity against Trichodenna viride and Stachybotrys Chartarum. Meanwhile, changing temperature within limits could have little affect the antibacterial activity of lotus seed polyphenols, and the antibacterial effect of lotus seed polyphenols was not obviously changed in the pH5-8. In addition, the MIC for five kinds of bacterias were as follow: Staphylococcus aureus, 0.3 mg/mL; Bacillus subtilis, 0.4 mg/mL; listeria spp, 0.4 mg/mL; Escherichia coli, 0.8 mg/mL and Salmonella typhimurium, 0.8 mg/mL.(5) The determination of the components of lotus seed polyphenols was studied by HPLC. The results showed that 4 kinds of polyphenol acids were determined in the lotus seed, including chlorogenic acid standard. The content of chlorogenic acid was 0.8 mg/100g. Flavonoids were determined in the lotus seed, including rutin standard. The content of rutin was 1.2 mg/100g. |
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