Extraction And Microencapsulation Of Pomegranate Seeds Polyphenols By Deep Eutectic Solvent

Pomegranate is widely planted in China,and pomegranate seeds account for about22%of the total fruit weight.Pomegranate seed is rich in phenols,which has the functions of anti-oxidation,anti-aging and bacteriostasis,and has a good application prospect in food,pharmaceutical and other industries.After processing and production,pomegranate will produce a large number of pomegranate waste residue in which the rich active substances are wasted.In order to solve the above problems,the extraction technology and biological activity of polyphenols from pomegranate seeds were studied,and pomegranate seeds polyphenols（PSP）were loaded into nanoparticles to provide a theoretical basis for further development and improvement of pomegranate seed polyphenols bioaccessibility.1.Using pomegranate seed as raw material,the process of extracting pomegranate seed polyphenols by ultrasound-eutectic solvent was optimized by response surface method,and the effects of different solvents were compared.The eutectic solvent was characterized by Fourier transform infrared spectroscopy.The results show that the molar ratio of urea to choline chloride is 2:1.The process parameters were selected as follows:water content 38%,ratio of liquid to material 31:1（m L/g）,extraction temperature 58℃,ultrasonic time 25min.Under these conditions,the extraction amount of polyphenols from pomegranate seeds was 12.90±0.12 mg·g^-1.Under these conditions,the extraction amount of pomegranate seeds polyphenols was 12.90±0.12 mg·g^-1,which was higher than that of water extraction(1.72±0.12 mg·g^-1)and ethanol extraction(3.15±0.14 mg·g^-1).2.Pomegranate seed polyphenols were purified by 8 kinds of macroporous resins with different polarity.The resin type,adsorption time,eluent,sample flow rate and elution flow rate were optimized,and the antioxidant and antibacterial activities of pomegranate seed polyphenols before and after purification were compared.The study shows that HPD-100 macroporous resin is suitable for the purification of pomegranate seed polyphenols,and the best purification process is as follows:elution is 70%ethanol solution,sample flow rate 1.0 m L·min^-1,elution flow rate 1.0 m L·min^-1.The IC₅₀ of DPPH and ABTS radical scavenged by PSP before purification was 30.91,18.82μg·m L^-1,and the IC₅₀ of DPPH and ABTS radical scavenged by PSP after purification was21.81,13.36μg·m L^-1.The bacteriostatic test showed that pomegranate seed polyphenols had certain inhibitory effects on S.aureus,E.coli,S.enteritis and S.typhimurium.3.Zein-chitosan nanoparticles loaded with PSP（Zein/Cs/PSP-NPs）were prepared by self-assembly method.The preparation method was optimized,and the particle size,PDI,zeta and entrapment efficiency were determined.The nanoparticles were characterized by scanning electron microscope,Fourier transform infrared spectroscopy and differential thermal scanner.The stability of nanoparticles was evaluated and their release behavior was evaluated by simulating gastrointestinal digestion test in vitro.The results show that when the mixture volume ratio of Zein to Cs is 1:4,the concentration of chitosan is 1.0mg·m L-1 and the concentration of polyphenol is 2mg·m L-1,the particle size is 367.80±6.00nm and the Zeta potential is 0.191±0.007m V.The results of SEM,FTIR and DSC showed that the nanoparticles were successfully prepared.The stability of nanoparticles was investigated by p H,Na Cl and storage time.The results showed that the nanoparticles were stable in strong acid and unstable in high salt environment.During0-45 days storage,the size of nanoparticles increased significantly,but had no significant effect on PDI and zeta potential.In the antioxidant test,and the DPPH clearance rate of DPPH was 74.32%after 7 days.The results of simulated gastrointestinal digestion test in vitro showed that Zein/Cs/PSP-NPs could release PSP continuously during the whole gastrointestinal digestion.