The Study Of Extraction And Properties Of Protein And Bioactive Substances On Moringa Leaves

Moringa leaf is a great potential plant protein sources,which are rich in fiber,protein,vitamins and trace elements.With high bioavailability,Moringa leaf is also recognized as a novel resource of food.In this paper,the extraction and properties of protein and natural products on Moringa leaves were studied,including the preparation of water-soluble protein and its functional properties,dynamics of total phenols and flavonoids by subcritical water extraction method,the separation and purification of total phenols and flavonoids and the content of total phenols and flavonoids,antioxidant activity and antibacterial activity of Moringa leaf extracts and so on.The specific studies were as follows:(1)Preparation and features of water-soluble protein of Moringa leafApplication of ultrasonic and microwave assisted extraction of protein was studied using dry Moringa leaves as a raw material by single factor experiment.We determined amino acids composition and heat distortion temperature of the Moringa leaf protein.The effects of pH,NaCl concentration,sucrose concentration and temperature on functional properties of Moringa leaf proteins were investigated.(2)Extraction of total phenols and flavonoids on Moringa leafIn this paper,hot water extraction,ultrasonic extraction and subcritical water extraction were used to extract effective ingredient on Moringa leaves,and the content of the three extracts of total phenols and flavonoids were determined.The results show that subcritical water extraction method could reduce the extraction time and has high extraction efficiency.(3)Kinetics of subcritical water extraction of total phenols and flavonoids on Moringa LeavesAccording to different temperature conditions of the concentration of active ingredient by means of the extraction in subcritical water over time,kinetic model of a subcritical water extraction of active ingredient was established:E=Ex(1-e-kt);The experimental proved that this kinetic model fitted well with the experimental data from the extraction.The model can estimate the yield of subcritical water extraction and effectively simulate the subcritical water extraction process.It provided a theoretical reference for the subcritical water extraction of active ingredients from plants for industrial applications and for expanding the scope of subcritical water extraction application.(4)Study of separation and purification total phenols and flavonoids of Moringa leafLiquid-liquid separating method was used to gradient crude extract of subcritical water extraction from Moringa leaf.The total phenols and flavonoids of ethyl acetate phase were isolated and purified by macroporous resin.The results showed that the adsorption equilibrium data were agreed with Freundlich adsorption isotherm well.The adsorption procedure was a spontaneously exothermic reaction with entropy decrease.Thus,low temperature is benefit to it.The results showed that resin was the suitable for purification of total phenols and flavonoids from Moringa leaf.The contents of total phenols and flavonoids of Moringa leaf product increased to 52.01%and 37.58%,respectively.(5)The content of total phenols and flavonoids,antioxidant activity and antibacterial activity of Moringa leaf extractsThe content of total phenols and flavonoids,antioxidant activity and antibacterial activity of Moringa leaf extracts were studied.The resutls showed the content of total phenols and flavonoids,antioxidant activity and antibacterial activity of extract of the ethyl acetate phase were higher than others.The purification is useless to enhance the antioxidant activity,but contribute to boost antibacterial activity.