Extraction,Biological Activity And Microencapsulation Of Polyphenols From Platycodon Grandiflorum

Platycodon grandiflorum is a kind of traditional medicine food homologous plant with edible,medicinal and ornamental value.It is distributed in most provinces of China,and also in Korea,Japan and the Far East of Russia.Modern studies have shown that Platycodon grandiflorum has a variety of pharmacological activities,such as antitussive,expectorant,lung and so on.Polyphenols are found in plant,which can prevent diseases.They mainly exist in the skin,root,leaf and fruit of plants.Polyphenols not only have antioxidant activity and scavenging free radicals,but also have good antibacterial and anti-inflammatory properties,it has been widely used in food,medicine and chemical industry.The content of polyphenols in Platycodon grandiflorum is rich.In this project,the drying treatment of Platycodon grandiflorum was screened,the extraction of polyphenols from Platycodon grandiflorum was optimized,and its biological activity was determined.The extracted polyphenols from Platycodon grandiflorum were made into microcapsules and applied in the production of cookies.The main research contents and results are as follows:(1)Selection of drying methods for Platycodon grandiflorumNatural shade drying,vacuum freeze drying,microwave drying,60?hot air drying,80?hot air drying and their effects on the properties,components and antioxidant activity of Platycodon grandiflorum were compared.80?hot air drying was confirmed as the economic and applicable drying method.The content of polyphenols,flavonoids and saponins of Platycodon grandiflorum after 80?hot air drying was the highest,and the antioxidant activity was the best.And the 80?hot air drying has the advantages of economy and fast.Therefore,the drying method of pretreatment of the extraction of Platycodon polyphenols is considered to be 80?hot air drying.(2)Microwave-assisted extraction process of polyphenols from Platycodon grandiflorumIn order to obtain more effective extraction method for polyphenols from Platycodon grandiflorum,the microwave-assisted extraction method was selected to extract the polyphenols from Platycodon grandiflorum.Based on single factor experiment,response surface methodology was used to optimize the extraction conditions by box Behnken central composite design.The response surface of ethanol concentration,microwave time,microwave power and solid-liquid ratio was established by single factor results,and the regression model was P<0.0001 and R² was 0.9651,which was extremely significant and highly fitting.The optimum extraction conditions were as follows:microwave power 210 W,material-liquid ratio 1:30 g/m L,the microwave time is 60 s,the ethanol concentration is 50%,and the number of extractions is 2 times.Under these conditions,the average extraction yield of polyphenols from Platycodon grandiflorum was 6.456 6 mg/g.(3)Biological activity of polyphenols from Platycodon grandiflorumThe biological activity of polyphenols from Platycodon grandiflorum was determined.The antioxidant activity of polyphenols from Platycodon grandiflorum was evaluated by measuring the iron reduction ability,superoxide anion scavenging ability,hydroxyl radical scavenging ability,DPPHfree radical scavenging ability,ABTS⁺scavenging ability,and the results showed that polyphenols from Platycodon grandiflorum have good antioxidant properties.It is dose-dependent.polyphenols from Platycodon grandiflorum have strong scavenging ability to O₂^-,OH,DPPHand ABTS⁺,and their IC₅₀ values are 5.303,0.001,0.136,0.002?g/m L,respectively.The anti-inflammatory ability of polyphenols from Platycodon grandiflorum was studied by macrophage RAW264.7.MTT test showed that polyphenols from Platycodon grandiflorum can enhance the viability of RAW264.7 cells,and the neutral red uptake test showed that polyphenols from Platycodon grandiflorum can enhance the phagocytic ability of RAW264.7 cells.In addition,the release of NO from RAW264.7 cells increased after stimulation by polyphenols from Platycodon grandiflorum,indicating that polyphenols from Platycodon grandiflorum have good anti-inflammatory ability.The antibacterial activity of polyphenols from Platycodon grandiflorum was evaluated by the filter paper method and the MIC method.The results showed that the inhibitory effects of polyphenols from Platycodon grandiflorum on the four pathogenic bacteria were as follows:Staphylococcus aureus>Bacillus subtilis>Pseudomonas aeruginosa>Escherichia coli.The MIC for Pseudomonas aeruginosa and Bacillus subtilis is 20 mg/m L,and the MIC for Escherichia coli and Staphylococcus aureus are 40 mg/m L and 5 mg/m L,respectively.(4)Preparation technology of polyphenols from Platycodon grandiflorum microcapsulesArabia gum and maltodextrin were used as wall materials,were used as wall cores,polyphenols from Platycodon grandiflorum microcapsules were prepared by freeze-drying method.The effects of wall material ratio,core wall ratio,solid mass fraction and p H value on the moisture content,repose angle and embedding rate of microcapsules were determined to determine the best microcapsule technology.The microcapsules were characterized by particle size analysis.The microcapsules were characterized by scanning electron microscopy and Fourier transform spectroscopy.The release and stability of Platycodon polyphenols microcapsules in vitro were studied.The optimal technological parameters of polyphenols from Platycodon grandiflorum microcapsules were determined:the ratio of wall to material is 1:1,the ratio of core to wall is 1:6,the mass fraction is 30%,and the p H value is 5,and the encapsulation efficiency of the microencapsulated Platycodon grandiflorum was 92.33%.Under this technological condition,the microcapsule complex emulsion is stable,the microencapsulation effect is good,the spherical shape is good,and has good sustained release effect and stability.(5)Application of polyphenols from Platycodon grandiflorum microcapsules in cookiesBased on the traditional cookie making,the polyphenols from Platycodon grandiflorum microcapsules was added to prepare the cookies which are rich in polyphenols.The effects of butter,sugar powder,egg liquid and microcapsule on the sensory evaluation of cookies were compared and analyzed.The optimal formula was determined as follows:50%butter,30%sugar,35%egg liquid and 11%microcapsule.The finished cookies have good color,appearance and taste,and are rich in nutrition.