Research On The Extraction,Antioxidant Activity And Application Of Polyphenols From Lotus Leaf

Lotus leaf is the leaves of the plant belonging to the nelumbo.It has a wide planting area,very rich in resources.At present,the development and utilization of lotus leaf in the domestic mainly depend on the rough processing,resulting in a lower degree of use of lotus leaf.Lotus leaf is rich in polyphenols,which have antioxidant,antibacterial,lipid-lowering diet,anti-radiation,enhance the body immunity,anti-inflammatory,anti-viral,anti-aging and other functions,with great application value.In this paper,lotus leaf was selected as the experimental raw material,and the extraction conditions of lotus leaf were studied.The antioxidant ability of the lotus leaf was studied by the antioxidant experiment in vitro.We preliminarily probed into the condition of preparing the microcapsules of polyphenol from lotus leaf,and successfully developed the preparation method of functional yellow wine with lotus leaf,and its physical and chemical indexes were studied.The main results of this paper are as follows:1.Optimization of extraction conditions of polyphenol from lotus leafWith lotus leaf as raw material,on the basis of the single factor test,factors of the response surface design were determined.The results showed that the optimum extraction conditions were as follows:extraction temperature was 47?,extraction time was 97 minutes,liquid ratio was 70 mL/g.Under the optimum process conditions,the theoretically predicted value of the extraction yield of crude polyphenol from lotus leaf was 54.12 mg/g.2.Study on antioxidant activity of crude polyphenol from lotus leafWith lotus leaf crude polyphenol as the research object,the effects on scavenging of hydroxyl radical,DPPH radical and ABTS radical were investigated.The result indicated that the scavenging ability of hydroxyl radical,DPPH radical and ABTS radical gradually increased with the increase of the concentration of lotus leaf crude polyphenols in the experimental concentration range,but at the same concentration,the effect on scavenging of free radical was lower than that of the control group using vitamin C.3.Study on the preparation and properties of lotus leaf polyphenol microcapsulesThe polyphenol microcapsules were prepared by using lotus leaf polyphenol as the core material,chitosan and sodium alginate as wall materials,and characterized by scanning electron microscopy(SEM)and Fourier transform spectroscopy(FT-IR).At the same time,the release of lotus leaf polyphenol microcapsules in vitro was studied.The results showed that lotus leaf polyphenol was successfully coated in microcapsules,and the embedding rate reached 70.04%.The study on release in vitro showed that lotus leaf polyphenol microcapsules can achieve the effect of delayed release.4.Preparation of rice wine containing lotus leaf polyphenolOn the basis of the traditional leaching brewing,the functional yellow wine with lotus leaf polyphenol was prepared by adding lotus leaf polyphenol.The effects of adding time and adding amount of lotus leaf polyphenol on the physical and chemical indexes of yellow wine were analyzed,gaining the optimal brewing conditions:at the end of fermentation of yellow wine,lotus leaf polyphenols were added,and the adding amount was 300 mg/L.The brewed wine was rich in lotus leaf polyphenol and its nutritional value was higher.The finished wine:alcohol of 12.2%vol.;total sugar of 15.10 g/L;total acid of 6.67 g/L;amino acid nitrogen of 0.42g/L;polyphenol content of 0.453 g/L;amino acid content of 3.64 g/L.Lotus leaf polyphenol yellow wine samples were detected 58 major volatile components.The number of volatile components detected was 18 more than that of the control group.