Effect Of Tween 20 On The Interfacial Properties And Stability Of Soybean Protein Emulsion

Soy protein is a high-quality vegetable protein resource.Emulsification is one of the most important functional properties of soy protein.Soy protein added to food can effectively improve the taste,stabilize the emulsification state of the system and extend the shelf life.The emulsifying properties of soy protein are affected by small molecule surfactants,and the mechanism of its influence is currently unclear,which limits the application of soy protein to a certain extent.This topic systematically studies the interaction between soy protein and Tween 20 at the molecular level.It is expected to reveal the key structural characteristics of proteins that affect the ability of Tween 20 to replace the interface,and to clarify the mechanism of Tween 20 interface substitution on the stability of protein emulsions.Provide a theoretical basis for expanding the application of soybean protein in the food industry.The study found that in the coarse emulsion system,the addition amount of Tween 20,Na Cl concentration,and p H can affect the replacement efficiency of the interface soybean protein(SPI).The interfacial substitution rate of the Tween 20 pair of SPI coarse emulsion after homogenization was 48.87%at the maximum,and the concentration(?)of the adsorbed protein at the interface was 3.02 mg/m~2.Alkaline or 0.1mol/L Na Cl conditions are more conducive to Tween 20 replacing SPI from the interface.Before homogenization,the highest substitution rate of Tween 20 interface SPI was 33.93%,and the lowest?value was6.39mg/m~2.The addition of Tween 20 hardly affects the stability of the coarse emulsion,while the addition of Tween 20 first increases the emulsion instability faster as the amount of Tween 20 added.Observation by laser scanning confocal microscopy revealed that the protein layer adsorbed on the emulsion interface after Tween 20 was significantly thinned.In the high-pressure homogeneous fine emulsion system,the effect of Tween 20 at 2.0%(w/v)on the interface SPI substitution is the best.At this time,the substitution rate is 41.29%and the?value is 2.66mg/m~2.The effect of the addition order of Tween 20 on the substitution efficiency of the interface SPI and the stability of the emulsion is completely different from that of the coarse emulsion system.The highest substitution rate of the interface SPI before adding Tween 20 is 90.67%,and the value of?is 0.17mg/m~2.Adding Tween 20 emulsion before homogenization is more stable than adding Tween 20 emulsion after homogenization.The substitution of Tween 20 for 7S component is stronger than that of 11S component,and the stability of 7S component emulsion is higher.Although the addition of Tween 20 reduces the absolute value of the potential of all emulsions,it can significantly improve the storage stability of the miniemulsion,which is mainly believed to be related to its ability to interact with the interface protein and reduce the hydrophobic interaction of the protein between the oil droplets.By moderately heat-treating SPI,sodium sulfite modification and succinylation modification,the hydrophobicity,free thiol content and protein chargeability of SPI surface were adjusted respectively,and then the modified SPI source was used to construct an emulsion simulation system.The effect of Tween 20 on the interface substitution law of modified protein and the stability of emulsion.The study found that the hydrophobicity of heat-treated SPI increased and the content of exposed sulfhydryl groups decreased,making it more difficult for Tween 20 to replace interface proteins;the surface hydrophobicity of sodium sulfite treatment SPI did not change significantly,but the increased content of exposed sulfhydryl groups led to more substitution Easy;the surface hydrophobicity of SPI after acylation modification is increased,the content of exposed thiol is reduced,but the absolute value of Zeta potential is significantly increased,it is more easily replaced by Tween20 from the interface,and the minimum value of emulsion?can be reduced to 0.34mg/m~2.Compared to the surface hydrophobicity and the exposed thiol content,the chargeability of the protein may be the most critical structural factor that affects the Tween 20 interface replacement ability.After adding Tween 20,the stability of the modified protein emulsion has been significantly improved.The mechanical strength of different protein oil-water interface membranes was analyzed using a Hake interface rheometer.The study found that SPI can gradually form a viscoelastic interface network structure at the oil-water interface,and the mechanical properties are getting higher and higher,while casein and Tween 20 can only form a fluid interface film with poor viscoelasticity.When Tween 20 and SPI are added to the oil-water interface at the same time,due to the faster adsorption of Tween 20 and stronger competitive adsorption capacity,only a fluid interface film can be formed.Adding Tween 20 after the SPI adsorbs to the oil-water interface will cause the interface membrane to stop increasing in viscoelasticity.Compared with SPI,the interface membrane rheological properties of all modified proteins were significantly worse,and Tween 20 also failed to change its interface membrane strength.