Physicochemical And Functional Properties Of Stauntonia Brachyanthera Seed Protein And Application In Lutein Encapsulation

Stauntonia brachyanthera Hand.Mazz.(S.brachyanthera)belongs to the genus Papaya of the genus Mutong.S.brachyanthera fruit seeds are rich in oil and protein,but are often directly discarded during the production process,causing a lot of waste of resources.In this study,S.brachyanthera isolated proteins and main protein components,including albumin,globulin,and glutelin,were extracted from the seeds of S.brachyanthera,and their physical,chemical,and functional properties were studied.The protein content of non-defatted and defatted seeds was 17.27±0.3%and 33.60±0.8%,respectively.The subunit molecular weight(MW)of the isolated protein and each component protein ranges from 11.0 to 51.0 kDa,with a balanced amino acid ratio.Except for methionine in albumin,its essential amino acid content is in line with WHO/FAO recommendations for adults.At the same time,isolated proteins,albumin,and glutelin showed similar secondary structure composition,X-ray diffraction peaks,and denaturation temperature.Albumin is the main storage protein in seeds,and its surface hydrophobicity(516.7±7.9),solubility,emulsifying ability(emulsifying ability index 110.9±1.6 m2/g,emulsion stability index 80.5±1.3%)and foaming ability(foaming capacity 679.1±53%)are higher than those of protein isolate and glutelin.At the same time,compared with some other plant proteins,the isolated protein has a better amino acid composition,higher foaming capacity(406.7±41%),water holding(4.66 g/g)/oil holding(9.06 g/g)capacity,and emulsifying properties(emulsifying ability index 99.6±1.5 m2/g).In addition,typical viscoelastic gel properties were found in protein isolates and albumins,where the storage modulus was dominant.These results show that protein isolates and albumin have potential as functional raw materials in the food industry.Subsequently,a new and stable proteoglycan nanoparticle through a heat induced self-assembly method using albumin(S.brachyanthera seeds albumin,SBSA),Gum Arabic(GA),and sodium carboxymethylcellulose(CMC-Na)was proposed.And were used for the encapsulation of lutein,a hydrophobic active ingredient.The preparation conditions were optimized,and stable nanoparticles were prepared at a mass ratio of SBSA:GA:CMC-Na at 30:15:2 and pH at 5.5,which exhibited good storage,pH and salt stability.The analysis of infrared spectrum and fluorescence spectrum showed that the main driving forces for the formation of nanoparticles include hydrogen bonding,hydrophobic interaction and electrostatic interaction.The drug loading and encapsulation efficiency of lutein in nanoparticles depend on the concentration of lutein added.The highest drug loading is 0.92±0.01%and the encapsulation efficiency is 83.95±0.07%.At the same time,the thermal stability of lutein was significantly improved after encapsulated by nanoparticles.After 21 days storage at 4,25 and 37?C,the retention rates of lutein were 86.95±2.4%,71.7±3.1%and 64.3±2.6%,respectively.The results of this study can provide some references for exploring the application of new sustainable protein resources from plants in encapsulation systems.