Extraction,Physicochemical Properties,Characterization And Biological Activity Of Pectin From Premna Microphylla Turcz Leaves

Premna microphylla Turcz.(PMT)belongs to the genus of Verbenaceae.It is mainly grown on hillsides,under forests or in barren hills.It does not require high soil quality and can grow well even in barren soil.It can be used as a plant to prevent soil erosion in deserted hills.PMT is rich in pectin,protein,cellulose,mineral elements,amino acids and biologically active substances,but the content of pectin in PMT leaves makes up 30%~40%.Pectin has physiological functions such as thickening,gelling,emulsifying,and anti-oxidation.It can be used in food,medicine or cosmetic industries.Further research on PMT leaves can improve its economic value,which is not only beneficial to protection of the ecological environment,but also helps people in mountainous areas get rid of poverty.At present,the research on pectin in PMT leaves is relatively dispersed.Studies will be carried out from the following aspects,such as pectin extraction optimization,decolorization and its characterization of physicochemical properties.Meanwhile,biological activity and functional characteristics of the extracted pectin will be further explored.The main conclusions are as follows:(1)Optimization of pectin extraction conditions and decolorization in PMT leavesThe two methods of directed drying and microwave inactivation of enzyme drying were used to treat PMT leaves,and the extraction conditions of pectin were optimized.Orthogonal test results show that the optimal conditions for acid extraction are as follows: hydrochloric acid solution pH 1.5,extraction temperature 90?,l liquid-solid ratio 50:1 mL/g,extraction time 3.5 h,and the extraction yield of pectin was 7% under the conditions.The result of response surface experiment showed that the optimum extraction conditions of microwave inactivating acid extraction method were as follows: extraction time 2 h,extraction temperature 90?,liquid-solid ratio 50:1 mL/g,hydrochloric acid solution pH 2.The extraction yield of pectin was 18.25% under the conditions.Microwave-inactivated enzymatic acid extraction of pectin has a high extraction yield,and the appearance of the product is lighter and pale yellow.Therefore,this method was selected as a method for extracting the pectin from PMT.In the study of decolorization of extracted pectin,3% activated carbon was added to the extract at 70? for 30 min.The decolorization effect was obvious.Different concentrations of ethanol have a decolorizing effect on the pectin after alcohol precipitation,of which 75% of the ethanol decolorization effect is obvious,and the pectin extraction rate is higher than the decolorization of activated carbon.So it's good to choose 75% of ethanol for pectin decolorization.(2)Characterization of physicochemical properties of pectin in PMT leavesThe results show the characterization of pectin physicochemical properties.It was determined that the quality of pectin extracted by microwave inactivating hot enzymatic acid meets national standards.Coomassie Brilliant Blue G-250 measured 9.8% of pectin protein content;and titration method of 62.50% pectin esterification,pectin is a high ester pectin;gel filtration chromatography results show that the average molecular weight of pectin was 18.35 kDa.Monosaccharide composition of pectin by Gas chromatography method was measured.The results showed that there are five kinds of monosaccharides contained in pectin,which are glucose,rhamnose,galactose,arabinose,and mannose.The ratio of the amounts of the substances was 8.07:2.96:2.05:1.17:1.04.The UV and IR spectra showed that the main absorption peaks of the extracted pectin and apple pectin were the same.(3)Preliminary study on biological activity and functional properties of pectinTo expand the application of pectin,the bioactivity of pectin was conducted by in vitro antioxidant capacity and antibacterial activity.Pectin has a certain antioxidant capacity.When the concentration of pectin solution was 1.00 mg/mL,the DPPH radical scavenging rate was 90.00%.The reducing power of pectin increased with the increase of the concentration of pectin solution.The experimental results from in vitro antibacterial activity show that pectin has no antibacterial activity against Escherichia coli,Staphylococcus aureus,and Micrococcus luteus.The experimental environment pH is 7,pectin has a protective effect on the activity of Nisin.The functional properties of pectin were studied.The results showed that when the concentration of pectin was 10.00 mg/mL,the water holding capacity(WHC)of pectin was 7.956 g/g,and the oil holding capacity(OHC)of pectin was 1.932 g/g.The concentration of 1% of the pectin solution foaming capacity of 4.00%,foaming stability of 10.00%;concentration of 2% of the pectin solution emulsifying ability of 38.70%,emulsion stability of 56.90%,which is pectin in The application of food industry provides a certain reference value.In my paper,optimization of extraction conditions,decolorization,characterization of physicochemical properties,biological activity and functional properties of pectin in PMT leaves were studied.This makes full use of pectin resources and provides a reference value for expanding the source of pectin raw materials.At the same time,the supply of pectin in our country is not in demand.If we can develop the products of PMT leaves pectin,it can promote the economic development of the local people,reduce the waste of resources and protect the ecological environment.