Effect Of Microwave And Microbial Pretreatment On Utilization Of Biomass Components Of Jerusalem Artichoke Straw

Jerusalem artichoke is considered as an ecological and economic crop because of its multiple ecological functions and free from pests and diseases.Therefore,its planting area has been gradually expanded.The cultivation of Jerusalem artichoke is also used to improve geological conditions,especially in saline,oil-contaminated,and coal-mining soils.In addition to producing edible tuber fruits rich in inulin,Jerusalem artichoke leaves and stalks were left with huge biomass.The leaves of Jerusalem artichokes are rich in bioactive substances,and the straw is usually considered to be used for the utilization of cellulose and hemicellulose.Therefore,it is necessary to adopt appropriate pretreatment methods to transform the straw for the degradation of lignocellulose and further utilization.In this paper,Microwave-assisted extraction technology was used to extract total flavonoids from Jerusalem artichokes leaves.The extraction conditions of total flavonoids from Jerusalem artichokes leaves were optimized by orthogonal experiment.Using fungus to pretreat Jerusalem artichoke straw,by changing the composition of straw,so as to affect its pyrolysis characteristics,to prepare Jerusalem artichoke straw materials with different characteristics.The details are as follows:1.The effects of extraction conditions on the extraction of total flavonoids from jerusalem artichokes leaves were analyzed.According to the results of single factor experiment,the optimal extraction conditions were determined by orthogonal experiment as follows:extraction temperature was 60℃,extraction microwave power was 300 W,extraction time was 30 min,ethanol concentration was 50%.The extraction rate of total flavonoids was 12.89%after verification.2.The results showed that DPPH scavenging ability at 10 mg/m L of flavonoids was equivalent to that of 2 mg/m L VC,and the iron reducing power of VC at 2 mg/m L of flavonoids was equivalent to that of VC at the same concentration,indicating that flavonoids from the leaves of jerusalem artichokes had good antioxidant activity in vitro.Flavonoids showed good bacteriostatic effect against Escherichia coli OP50,Staphylococcus aureus and Pseudomonas aeruginosa PA14,and they were concentration dependent.The inhibitory effect on Escherichia coli JY26 was general.This may be due to differences in the way flavones react with the cell walls and membranes of different bacteria.3.The kinetic changes,gas spillover changes and the composition changes of pyrolysis products during the pyrolysis process of straw were studied by thermogravimetric（TG）,thermogravimetric infrared（TG-FTIR）and pyrolysis gas chromatography-mass spectrometry（Py-GC/MS）.4.The electrochemical properties of carbon from artichoke straw treated by Aspergillus Niger were discussed.According to CV curves（Cyclic Voltammetry curves）,the catalytic response of carbon（JASC-10）modified electrode treated with Aspergillus niger for 10 days to H₂O₂ is several times higher than that of bare gold electrode.However,The JASC-20～JAS-60 modified electrode only slightly improved compared with JASC-10.This indicated that the straw carbon was most affected by Aspergillus Niger treatment for 0 to 10 days.Finally,the structures of JASC-0,JASC-20 and JASC-60 were observed and compared by field emission scanning electron microscopy.It was found that the carbon pores of the straw treated by Aspergillus Niger became larger and the pore walls were significantly thinner.