Study On Extraction And Microencapsulation Of Flavonoids From Tillering Onion

Tillering onion(Allium cepa var.Aggregatum),commonly known as bulbous onion,Maocong,wheat onion and so on.There are many kinds of active components in tillering onion,among which flavonoid is one of them.Flavonoid is a kind of natural antioxidant existing in plants.It can quench the extra free radicals produced by diseases in the body,so as to prevent and treat diseases.However,flavonoids are easy to be affected by the external environment.Because of its poor stability and difficulty to preserve,the microencapsulation of flavonoids can increase the stability of flavonoids and prolong its storage time.There are few studies on the separation and purification of Flavonoids from tillering onion,which limits its further application.In this project,flavonoids from tillering onion were extracted and purified and microencapsulated by using tillering onion as research material.Through the gastrointestinal fluid simulation test of tillering onion flavone microcapsules,the digestion in vivo was studied to provide a reference for the comprehensive utilization and development of tiller onion.In this experiment,cellulase method,reflux method and ultrasonic method were used to extract flavonoids from tillering onion,and the content of flavonoids in tillering onion was used as the evaluation standard to select the best extraction method and optimize the parameters by response surface.The results showed that cellulase method:enzyme dosage 0.6 mg/g,p H 5,enzymolysis temperature 53?,enzymolysis time 2.8 h,flavone content 5.309 mg/g;Reflux method:extraction time 4.2 h,liquid-solid ratio 26:1,extraction temperature 69?,ethanol concentration 68%,flavone content 5.719 mg/g;Ultrasonic method:liquid-solid ratio 21:1,ethanol concentration 80%,extraction time 49 min,ultrasonic power 220 W,flavone content7.496 mg/g.In summary,the best extraction method is ultrasonic method.HPLC was used to determine the contents of three standard substances in the sample by external standard method:rutin 1.8250 mg/g,quercetin 2.3462 mg/g,kaempferol 0.8555 mg/g.However,in the chromatogram of the sample,there are still three unknown peaks,which need further analysis.In vitro antioxidant activity of flavonoids from tillering onion showed that the maximum DPPH scavenging rate was 89.35%.The maximum scavenging rate of hydroxyl radical was76.12%.The maximum scavenging rate of superoxide anion radical was 85.43%.The maximum scavenging rate of ABTS~+was 76.26%.The maximum nitrite removal rate was 72.11%.But also has strong reduction capability.The microcapsule of flavone was prepared by the method of sharp hole-coagulation bath.The technical parameters of flavonoids microcapsule for tillering onion were determined by response surface optimization test:The concentration of sodium alginate was 1.50%,the ratio of core to wall was 1:3,the concentration of calcium chloride was 2.0%,and the dosage of emulsifier was 1.00%,the entrapment efficiency of flavonoids microencapsulated in tillering onion was 75.472%.The physical and chemical properties of tiller onion flavonoid microcapsules and the digestion test of simulated gastrointestinal fluid in vitro were detected,and the whole structure of tiller onion flavonoid microcapsules was analyzed by scanning electron microscope.The results showed that the microencapsulated state was round granular,and the color was basically the same as that of the lyophilized powder after flavone purification.The particle size,water content,density and angle of repose were 0.6±0.1 mm,2.29%,0.541 g/cm~3 and 32.91?.Through the results of SEM after microencapsulation,we can see that the forming effect of the whole structure is better,and the embedding rate is also relatively good.The test results of microencapsulated simulated in vitro gastrointestinal fluid release show that the released amount of tillering onion flavone microcapsules after digestion in gastric juice for 11 h is only11.83±0.5054%,while the release amount in intestinal fluid can reach 85.93±0.8488%.Therefore,it can be concluded that the microcapsules of tillering onion flavonoids prepared by the sharp hole method can achieve a good release effect in the simulated intestinal fluid.