| Piper betle, , has been massively planted since ancient China. The plant can be used either as an ornamental plant or as medicine. Nowadays, the deep processing of Piper betle is lagging behind,and it merely has no high value-added products. This article uses fresh Piper betle to extract its essential oil, studies the optimum technology to extract essential oil of Piper betle by simultaneous distillation and extraction technology, and measures the bacteriostat and antioxidant activity, in order to offer technical support to the deep processing of Piper betle and to provide basic research data for follow-up development of high value-added products.We have studied the impact of five extraction conditions, including particle sizes of materials, 'solid-liquid ratio, ultrasonic time, distillation time and amount of salt added, on extraction ratio of essential oil of Piper betle by utilizing simultaneous distillation and extraction technology and optimizing with single factor tests. On this basis, we use response surface software Design-Expert and select the four factors and three levels of Box-Behnken Design (BBD) to optimize the test factors for the essential oil of Piper betle. The test results are as follows: the crushing particle size is 64.50 meshes, solid-liquid ratio is 8.29:1, ultrasonic time of raw material is 51.05 min, and under the condition of simultaneous distillation and extraction time at 8.54h, the optimal value of response surface theory is 21.87mg/g and the average value of experimental verification is 21.65mg/g. Among the GC-MS results, 41 substances in total have been detected, among which the content of isoeugenol is 70.03%, chavicol 10.52% and acetyl eugenol 7.04%.We have comprehensively analyzed the antioxidant capacity of natural essential oil of Piper betle. Both the total antioxidant activity and total reducibility of the natural essential oil is weaker than those of other three antioxidants, the ability to eliminate [ OH] is stronger than that of others, and the ability to eliminate [O2-ˇ] at 0.1% is stronger than that of BHT but equivalent to that of PG and Vc; at 0.2%, it is stronger than that of other three antioxidants. At 0.4% - 1%, it is stronger than that of BHT and PG but weaker than Vc.We have studied the application of essential oil of Piper betle in lipid anti-oxidation to lard, soybean oil and peanut oil. Adding a proper amount of essential oil of Piper betle is conducive to anti-oxidation of lipid with a dose-response relationship. In the systems of three lipids, citric acid and Vc have synergism to natural essential oil of Piper betle. In the lard system, the synergism of citric acid is stronger than that of Vc; in soybean oil and peanut oil system, the synergism of Vc is stronger than that of citric acid. In addition, low temperature preservation is beneficial to the antioxidant effect of essential oil of Piper betle on lipid storage.We have studied the inhibiting effect of natural essential oil of Piper betle to growth of bacteria and fungi. We select candida albicans, escherichia coli,escherichia coli 0157, staphylococcus aureus and streptococcus faecalis as the bacteria and beer yeast as the fungus. The experimental results show that: when the bacterial concentration is 106 pcsˇmL-1 the inhibition zone of essential oil of Piper betle on candida albicans is 34mm, and the minimum inhibitory concentration is 0.75mg/mL; the inhibition zone on escherichia coli is 52mm and the minimum inhibitory concentration is 0.75mg/mL; the inhibition zone on escherichia coli 0157 is 38mm and the minimum inhibitory concentration is 1.25mg/ml; the inhibition zone on staphylococcus aureus is 45mm and the minimum inhibitory concentration is 0.75mg/mL; the inhibition zone on streptococcus faecalis is 35mm and the minimum inhibitory concentration is 0.5mg/mL; when the concentration of fungus is 106 pcsˇm/L-1, the inhibition zone of essential oil of Piper betle on beer yeast is 40mm and the minimum inhibitory concentration is 0.75mg/mL. |
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