Preparation And Modification Of Momordica Grosvenori Seed Protein

Momordica grosvenori is one of the first plants listed as dual-purpose medicine and food in China.It has rich nutritional value and has the effects of clearing heat and moistening lung,moistening intestines and defecating stool,relieving cough and resolving phlegm.With the health value of Momordica grosvenori recognized by people,the processed products related to Momordica grosvenori are becoming more and more popular in the consumer market.However,with the development of Momordica grosvenori,Momordica grosvenori seeds,as waste in production and processing,have not been fully utilized,causing pollution to the environment and greatly limiting the in-depth development of Momordica grosvenori.In view of this,the protein from Momordica grosvenori seeds(MSP)was extracted by the alkali solution and acid precipitation method,the extraction process was optimized through single factor and response surface experimental design,and the functional properties of the protein were compared with with soybean protein isolate(SPI).On this basis,the covalent complex of Momordica grosvenori seed protein and rutin was prepared.And its physicochemical properties were systematically measured.Then,the sunflower oil-based Pickering emulsion was constructed with the complex as the emulsifier,and characterized.The protective effect of the Pickering emulsion on Astaxanthin was also evaluated.The main research results are as follows:(1)Momordica grosvenori seeds were rich in protein(13.42%),which was mainly composed of albumin,gliadin and glutenin.Electrophoresis analysis showed that Momordica grosvenori seed protein had three main subunits with molecular weights of 18.5 KDa,34.5 KDa and 50.5 KDa,respectively.Using defatted Momordica grosvenori seed powder as raw material,Momordica grosvenori seed protein could be extracted by the alkali solution and acid precipitation method.Through single factor and response surface experiment design,the effects of extraction time,extraction temperature,p H and liquid-solid ratio on protein extraction rate were investigated,and the optimum extraction process was determined as follows: extraction time 2 h,extraction temperature 37 ?,p H 10.0,liquid-solid ratio 17.5.Under these conditions,the protein extraction rate was 63.33%.,close to the theoretical prediction.(2)The functional properties of Momordica grosvenori seed protein were studied systematically.It was found that the solubility of Momordica grosvenori seed protein was similar to that of soybean protein isolate.the emulsifying and foaming properties of Momordica grosvenori seed protein were better than that of soybean protein isolate,and its water-holding capacity and oil-holding capacity were weaker than soybean protein isolate.The hardness,elasticity and cohesion of the two gels are similar.The viscosity of Momordica grosvenori seed protein was better than that of soybean protein isolate,but its stickiness,chewiness and resilience were lower than that of soybean protein isolate.When Momordica grosvenori seed protein was hydrolyzed by pepsin and trypsin,with the extension of hydrolysis time,the degree of hydrolysis of Momordica grosvenori seed protein increased with the extension of hydrolysis time,and then tended to be stable,and the hydrolysis effect of pepsin was better.The hydrolyzed product had strong DPPH and hydroxyl radical scavenging capacities,and could chelate iron and copper ions.And the antioxidant activity of the hydrolysate was closely related to the hydrolase type and the hydrolysis time.The results show that Momordica grosvenori seed protein is a kind of high quality plant protein resource,which can be used in the production of antioxidant peptides.(3)The covalent complex of Momordica grosvenori seed protein and rutin could be prepared by the alkali induction method,which was proved by UV and IR analysis.The total phenol content,reducing power and ABTS radical scavenging ability of the complex were positively correlated with the amount of rutin added in the preparation process.The complex could be used as emulsifier to construct Pickering emulsion.The formation of the emulsion was closely related to the concentration of the complex and the volume fraction of the oil phase.The stability and the protective effect of astaxanthin were positively correlated with the total phenol content of the complex,which was significantly higher than that of the emulsion stabilized by Momordica grosvenori seed protein.The emulsion system can be used for nutraceutical delivery.