The Separation,analysis And Antibacterial Mechanism Of Seed Melon Pectin Oligosaccharide

Seed melon pectin oligosaccharide(Sm-POS)is an oligosaccharide with certain functional activity that is degraded into a lower molecular weight range of seed melon pectin.In recent years,due to the function of pectin oligosaccharide,the related research on pectin oligosaccharide produced by incomplete degradation of pectin produced from fruit and vegetable peel residue and other raw materials has attracted extensive attention.This paper takes the Xin Jiang abandoned seed melon by-products as experimental materials,use of low cost and environmental protection of the immobilized enzymatic preparation of Sm-POS,select the best carrier materials,immobilized enzyme and immobilized enzyme in materials preparation,using the immobilized enzymatic preparation of Sm-POS.The specific structure of the active components of Sm-POS,the separation and purification of crude oligosaccharides and a series of structural analysis methods were used to determine the specific molecular structure and composition of the crude oligosaccharides,and the verification of its antibacterial activity and antibacterial mechanism laid a foundation for the application of Sm-POS in the storage and preservation of melons and fruits in the food industry.The main conclusions are as follows:1.By SA,CS and preparation of spherical porous r GO materials for immobilized enzyme carrier,and the three different conditions of immobilized carrier material is optimized,the relative enzyme activity of different carrier for immobilized enzyme stability and circulation service life evaluation,select best carrier materials,immobilized enzyme and immobilized enzyme material preparation.The experimental results show that the spherical porous r GO can be used as the best immobilized enzyme carrier material in this experiment.Compared with the free enzyme,the thermal stability and p H range of the immobilized enzyme prepared by this carrier are greatly improved.After 10 cycles,the relative enzyme activity remains above 87%.After stored for 30 days,the enzyme activity only lost 20%,which has a good application prospect.2.The hydrolysate of seed melon pectin was hydrolyzed by immobilized enzyme method and the best hydrolysis conditions were determined according to the bacteriostatic effect of the hydrolysate of seed melon pectin obtained under different hydrolysis conditions on E.coli and S.aureus.The results showed that the optimal conditions for the preparation of the hydrolysate of seed melon pectin by immobilized enzyme method were p H 4.0,temperature 45~oC,and the amount of immobilized enzyme was 0.02 g/m L,respectively,the hydrolysis time of E.coli and S.aureus were both 180 min.Under these conditions,the hydrolysis of seed melon pectin showed good antibacterial activity against both Escherichia coli and S.aureus.In order to further study the molecular structure of the active components of the hydrolysate of seed melon pectin with antibacterial effect,the HPD-750 macroporous resin column was used to elute the hydrolysate of seed melon gum with 95%ethanol solution,and then the hydrolysate of seed melon pectin was separated and purified by gel chromatogrhy.The active components of Sm-POS with antibacterial activity were determined by the antibacterial experiment results.The molecular structure of the active component Sm-POS was analyzed by FT-IR,NMR and LC/MS and other analytical methods.The results showed that the active component SM-POS-2 with antibacterial activity was pentagosaccharide oligosaccharide composed of 2galacturonic acids,1 glucose,1 arabinose and 1 xylose.3.The immobilized enzymatic preparation of the Sm-POS-2 study of antibacterial activity,Sm-POS-2 has good antibacterial activity,effect on inhibition of E.coli and S.aureus were started in demurrage and the minimal inhibitory concentrations(MIC)to E.coli is 25.0 g/L,the minimal inhibitory concentrations(MIC)to S.aureus is 50.0 g/L.From scanning electron microscopy(FESEM)in addition,the cell growth curve and the change of flow cytometry analysis results can be seen thatt the inhibitory effect of the active component of Sm-POS on E.coli and S.aureus was mainly caused by the shrinkage or rupture of cell membranes,which resulted in apoptosis or necrosis of the bacterial cells.