Approach And Application Of Ethanol-Induced Assembly Of Soybean ?-Conglycinin To Enhance Its Emulsification Properties

In the food field,the research of emulsion has always received extensive attention.Emulsions stabilized by the plant protein caters to the public's demand for natural health and green environmental protection,and is widely used in food,cosmetics,pharmaceuticals,coatings and agrochemicals.Among them,soy protein,as a typical representative of plant protein,has good emulsifying properties and biocompatibility,and is more and more widely used in food emulsion formulations.However,protein-based emulsions are easily affected by environmental factors(e.g.,temperature,pH,and ionic strength).So far,researchers have used various methods such as physical,chemical and biological methods to improve the stability of protein-based emulsions or the emulsifying properties of proteins.Ethanol treatment,as a physical means of modifying proteins,is often used to study the effects of protein structure.However,no relevant reports have been found on the emulsification of soybean ?-conglycinin(SC,one of the main storage globulins of soybean protein)by ethanol treatment.Therefore,this paper reports that the use of ethanol(20-80%,v/v)can induce SC aggregation and significantly improved the emulsification performance and interfacial behavior of the protein.Based on this,protein-polyphenol co-assembled nanoparticles were prepared,and then Pickering high internal phase emulsions(HIPEs)with superior antioxidant properties were constructed.Firstly,we investigated the ethanol-induced disassembly of SC at protein concentration(c)of 1.0 wt % but varying ethanol values([E])of 20–80%,as well as the reassembly of ethanoltreated SC.The influence of the ethanol treatment on the physicochemical and structural properties of SC was characterized.Next,the emulsifying and interfacial properties of these ethanol-treated SC(E-SC)samples were evaluated in terms of emulsification performance and interfacial stabilization,at two oil volume fractions(?)of 0.2 and 0.8.As expected,the treatment led to an [E]-dependent aggregation of SC,and formation of larger particles with more compact structure and higher in surface hydrophobicity.In both cases,the ethanol-treated SC showed greatly improved emulsification performance and interfacial stabilization.Even at a low concentration of 0.5 wt%,the ethanol-treated SC could still produce a kind of fine emulsions(produced by micro-fluidization),or high internal phase emulsions with a selfsupporting gel network that could resist the disruption of 6 M urea and the minimum concentration of E-SC stabilized HIPEs can be as low as 0.05 wt%.The improvements were largely due to the facilitated formation of bridged emulsions,via the strengthened Pickering stabilization by ethanol-induced aggregation.The results demonstrated that the ethanol pretreatment can be applied as an effective modification to remarkably improve the emulsifying properties of SC,through the strengthening of its Pickering stabilization.Then,the nanoparticles with a representative polyphenol((-)-epigallocatechin-3-gallate;EGCG)encapsulated were fabricated through an ethanol-mediated dissociation and reassembly process of SC.Characterized its physicochemical and structural properties.The results show that spherical co assembled nanoparticles can be obtained by this method.With the increase of the initial concentration of EGCG,the size of the co-assembled particles,the loading of EGCG,the protein solubility and the absolute value of the ?-potential were gradually increased,and the surface hydrophobicity decreased sharply.EGCG did not change the secondary structure of SC.The research results will help to develop new nanoparticles and Pickering stabilizers with antioxidant capacity.Finally,SC-EGCG co-assembled nanoparticles were used as the antioxidant Pickering stabilizer,and polyunsatuated fatty acid-rich flaxseed oil was used as the oil phase,emulsions at ? = 0.2 or 0.8 and a protein concentration in the aqueous phase of 1.0 wt% was prepared by micro-fluidization or one-step shear homogenization method.Then,the relevant properties of emulsions stabilized by co-assembled nanoparticles formed under the addition of initial EGCG concentrations were studied.The results show that the emulsions were extraordinarily stable against heating or long-term storage.The as-fabricated HIPEs showed an excellent protection to ?-carotene(encapsulated in oil phase)against heating,as well as an inhibition of lipid oxidation.The oxidation protection was in an EGCG concentration dependent manner.The results would be of interest for providing a novel strategy to fabricate functionalized Pickering HIPEs as potential containers or delivery systems for lipophilic nutraceuticals and oxidatively unstable grease.In summary,this article not only found that ethanol-induced dissociation and recombination of SC can significantly improve the emulsification performance and interfacial behavior of SC,and increase the gel network strength of HIPEs stabilized by SC.It proves that ethanol treatment is a development with excellent emulsification performance.A promising and effective strategy for soy protein products.It also proved that the ethanol treatment strategy can be used to construct soy protein nanoparticles,as an effective encapsulation and delivery carrier for active substances,and for the preparation of bifunctional stabilizers.The findings suggest a novel strategy to fabricate a kind of novel antioxidant Pickering HIPEs stabilized by food grade particles with a promising potential to be applied in food formulations,and have broad application prospects in food or other related fields.