| China is a country with huge groundnut production.Peanuts are grown here with a large area,many varieties,and abundant resources.However,due to difficulties in expanding production,low effective component extraction rates,and differences between peanut varieties,peanut shells,which are appendages to peanuts,have extremely low utilization efficiency and serious waste of resources.In recent years,as the concepts of green chemistry and low-carbon life have gradually become popular and become the mainstream of society,people have paid more and more attention to the rational and rational reuse of waste resources.The full and reasonable application of resources has become more and more important.In this study,peanut shell was used as the raw material,and the representative flavonoids-luteolin in it were subjected to green extraction and purification,Nano-crystallization,and Pickering emulsion preparation,etc.,which provided a feasible solution for the deep processing of peanut shell resources and high value-added reuse.The results of the study are as follows:1 Ultrasonic-microwave-assisted surfactant extraction was used to extract luteolin in peanut shells.Through comparison of pre-experiments,the dodecyldimethylbetaine aqueous solution was first determined as the extraction solvent and ultrasonic-microwave-assisted surfactant extraction was used as the extraction process.Then based on the response value of luteolin,the Box-Benhnken response surface design optimization method was used to optimize the main factors affecting the luteolin extraction rate in this process,and the best extraction process was:Dodecyl dimethyl betaine aqueous solution was 2.8%,liquid-to-material ratio was 24.1/1 mL/g,extraction time was 9.77 min,and microwave power was 845.2 W.According to confirmatory tests,the extraction rate of luteolin was 2.92±0.12 mg/g under the optimal process conditions.The obtained luteolin extract solution was concentrated and dried,and then 10 times the volume of acetone was added for pretreatment to increase the purity of luteolin in the extract to 31.7±1.21%.Then,under the guidance of the literature,the enriched luteolin extract was sequentially subjected to the AB-8 resin adsorption,ethyl acetate extraction,and recrystallization processes to obtain yellow luteolin crystals with a purity of 93.14±3.16%.2 The study first took luteolin in peanut shells as raw materials,and then carried out single-factor optimization experiments by using the main factors that can affect the average particle size as optimization conditions.Finally,luteolin nanoparticles were successfully obtained,and the optimal process conditions were optimized for:Ethanol and deionized water were used as solvents and anti-solvents,PVP-k30 was used as a surfactant,y-cyclodextrin was used as a lyophilized protection agent,the concentration of luteolin-ethanol was 4 mg/mL,and the sedimentation temperature was 20℃.PVP-k30 concentration was 0.075%,antisolvent to solvent volume ratio was 6/1,titration speed was 10 mL/min,rotor speed was 2000 r/min,settling time was 25 min,The mass ratio of y-cyclodextrin and luteolin was 7/1.In the luteolin suspension prepared under this optimal condition,this nanoparticle was re-dissolved in deionized water with the average particle size was 127.5±23.1 nm.3 The obtained luteolin nanoparticles were analyzed by SEM,FTIR,TG-DSC and GC,and the results showed that the degree of solvent residue in the luteolin nanoparticles prepared by applying this method met food standards.The luteolin molecules in the nanoparticles are amorphous,and the thermal characteristics have also changed.From the research results of saturation solubility,dissolution and bioavailability,the saturation solubility of luteolin nanoparticles in deionized water is 149.69±12.6 μg/mL,and the changes in solubility and crystalline state have greatly improved its solubility and bioavailability in rats.In addition,the inhibition of rat liver microsome lipid peroxidation in vitro was also significantly improved.4 Pickering emulsions with luteolin nanoparticles as stabilizers were successfully prepared,and the best process was optimized as follows:high pressure homogenization was used as the emulsification method,and the mass ratio of luteolin nanoparticles,pine nut oil,and deionized water was 4.8/1/10(mg/g/g).The preparation process was first prepare a luteolin nanosuspension by fine-tuning the antisolvent recrystallization method,adjust the suspension concentration,add citric acid to adjust the suspension pH,and then pour the suspension and pine nut oil into the container in proportion for pre-emulsify and emulsification process,the Pickering emulsion is finally obtained.The average diameter of the emulsion droplets prepared under the optimal conditions was about 125 nm.Transmission electron microscopy and fluorescence confocal microscopy results show that the luteolin nanoparticle-stable Pickering emulsion was successfully prepared.The emulsion has good stability in simulated gastric fluid and simulated intestinal fluid.The stability results under various conditions show that under non-extreme storage conditions,the emulsion has excellent storage stability and can effectively retard the rancidity of pine nut oil under accelerated oxidation conditions. |
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