| As a traditional Chinese medicinal material rich in bioactive compounds,Macleaya cordata（Willd.）R.Br.has high value.However,the traditional extraction methods have the disadvantages of low efficiency,long time-consuming and polluting the environment.Moreover,the solid residue after extraction is often discarded,which may pollute the environment.In recent years,subcritical water technology has attracted more and more attention of scholars.On the one hand,because subcritical water is at high temperature and high pressure,it has some characteristics that normal water does not have,such as low polarity and high mass transfer efficiency,which makes subcritical water similar to low polarity organic solvent and can efficiently extract natural organic components,such as essential oils,phenols,polysaccharides,etc.Moreover,it uses water as the extraction medium,which has the advantages of low cost,green.On the other hand,subcritical water can also be used as a reaction medium to treat biomass,plastics,petrochemical resources etc.Under the hydrothermal treatment,valuable products such as biomass oil,fuel gas and solid fuel can be obtained and recovered.Subcritical water process also provides ideas for the comprehensive utilization of Macleaya cordata（Willd.）R.Br..In this experiment,phenols were extracted from Macleaya cordata（Willd.）R.Br.by subcritical water process.In the first part of the experiment,the effects of subcritical water conditions on the yield of phenols were studied.The single factor method and response surface method showed that the extraction temperature,extraction time and liquid-to-solid ratio had a dual effect on the yield of phenols,and the extraction temperature had the most significant effect among the three factors.When the extraction temperature was 197 ℃,the extraction time was 43 min and the liquid-tosolid ratio was 21 m L/ g,the yield reached the maximum,which was 84.78 mg gallic acid equivalent /g.Then,through LC-MS / MS analysis,it was determined that the main phenolic components in the extract were quinic acid and rosmarinic acid.Finally,the differences in phenolic yield of the extracts by subcritical water extraction and two traditional extraction methods（ethanol extraction,hot water extraction）were compared.The results showed that the former has higher yield.In the second part of the experiment,the effects of extraction temperature（130,160,190,220 ℃）,extraction time（15,30,45,60 min）and extraction methods（subcritical water extraction,ethanol extraction,hot water extraction）on the abilities of extracts to scavenge DPPH and ABTS free radicals were studied.The results showed that with the increase of temperature and time,the antioxidant activity of the extracts increased first and then decreased,and it was preliminarily inferred that it had a certain positive correlation with the yield of phenols.By comparing the difference of the abilities of extracts by different extraction methods to scavenge DPPH and ABTS free radicals,it could be found that the extract by subcritical water had better antioxidant activity.In the third part of the experiment,the inhibitory effect of the extracts extracted at130,160,190 and 220 ℃ on Staphylococcus aureus,Escherichia coli,Penicillium citrinum and Aspergillus niger was studied.Through qualitative experiments,it could be found that under the action of the medium with a concentration of 75 or 150 mg/m L,the experimental groups of Staphylococcus aureus and Escherichia coli had bacteriostatic circles,and the growth of Penicillium citrinum and Aspergillus niger colonies were also inhibited respectively.Further,through quantitative analysis,it could be found that the antibacterial activity of the extract extracted at 190 °C was the best,and the minimum inhibitory concentrations for Escherichia coli,Staphylococcus aureus,Penicillium citri and Aspergillus niger were 9.375 mg/m L,4.6875 mg/m L,9.375 mg/m L and 18.75 mg/m L respectively.Moreover,compared with the extract by hot water extraction,the extract extracted at 190 ℃ had better antibacterial activity.In the fourth part of the experiment,the element and ash contents of residual solids treated at different temperatures were determined.Through references and theoretical calculation,it was concluded that the mass fraction of C element and theoretical high calorific value（HHV）of residual solid treated at 190 ℃ were the maximum.HHV was23.38 MJ/kg and the energy recovery rate was 71.32%.And by determining the ratio of H/C and O/C,it could be concluded that the residual solid belonged to peat. |
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