Application Of Soy Protein Isolate In Preparation Of Mayonnaise-like Emulsions With High Freeze-Thaw Stability

Mayonnaise is a kind of emulsion food with high-oil phase that the public likes.It is often stored in freezing conditions to increase its shelf life.During the freeze-thaw process,instable phenomenon such as demulsification often occurs in the mayonnaise,which affects its quality.In recent years,the preparation of low-cholesterol mayonnaise-like emulsions with high freeze-thaw stability has become a research hotspot in food industry.In this paper,the soy protein isolate?SPI?was used as an emulsifier.For particle characteristics,emulsifying performance,physicochemical properties and freeze-thaw stability of the high internal phase emulsions?HIPEs?,acid-heated?p H 3.0?soybean protein isolate?AHSPI?had great advantages,and it could be used to prepare the low-cholesterol mayonnaise-like emulsions with high freeze-thaw stability.Firstly,the particle characteristics,emulsifying properties of the p H 7.0 heat-induced soy protein isolate?HSPI?,the acidic?p H 3.0?native soy protein isolate?ANSPI?and the acid-heated soy protein isolate?AHSPI?were analyzed,including the freeze-thaw ability of the HIPEs??=0.80?stabilized by them.The results show that:AHSPI had larger average particle size?D_h?,higher surface hydrophobicity?H₀?,smaller Zeta-potential,good solubility and better emulsifying performance.The HIPEs stabilized by AHSPI had lower Surface Coverage?SC%?and higher Absorbed Protein?AP%?.AHSPI acted as a better Pickering stabilizer than ANSPI and HSPI.At the same time,the minimum protein concentration?c?of the HIPEs stabilized by AHSPI could reach to 0.2 wt%,and the highest oil fraction???could reach to 0.89.The HIPEs stabilized by AHSPI had strong gel network structure.In a certain range,the increase of the protein concentrations?0.2?2.0 wt%?and oil fractions??0.75??0.85?would enhance the gel network structure.The HIPEs stabilized by AHSPI had better freeze-thaw stability than the HIPEs stabilized by ANSPI or HSPI,owing to the strong gel network structure and stable interfacial layer.So AHSPI could be a wonderful choice to replace egg yolk for preparing mayonnaise-like emulsions with high freeze-thaw stability.Secondly,AHSPI was used to replace egg yolk entirely for preparing low-cholesterol mayonnaise-like emulsions simulating the mayonnaise system,which had better freeze-thaw stability than the mayonnaise prepared in the laboratory.The minimum protein concentration?c?for achieving freeze-thaw stability could reach to 0.3 wt%.The appearance and microstructure of the emulsions remained the same nearly before and after freeze-thaw,only the average droplet size of the emulsions increased slightly.And with the increase of the protein concentrations?0.3?4.0 wt%?,the viscoelasticity and apparent viscosity of mayonnaise-like emulsions increased,the freezing points of the emulsions decreased.Especially,the rheological property and texture of the mayonnaise-like emulsion at 4.0 wt%was similar to those of the lab-made mayonnaise.The average droplet size and texture of the mayonnaise-like emulsions could be adjusted by changing the protein concentrations in a certain range.At the same time,the mayonnaise-like emulsions had good long-term storage stability,which was conducive to extending their shelf life.The key for mayonnaise-like emulsions had better freeze-thaw stability was that the emulsions stabilized by AHSPI had more stable and thicker interfacial layers than mayonnaises.Finally,in order to improve the similarity with mayonnaise,2.0 wt%of chitosan?CS?and2.0 wt%of AHSPI were mixed to prepare HIPEs??=0.75?with great freeze-thaw ability in one-step emulsifying method.With the increase of the ratios of CS and AHSPI?0:1?1:1?,the average droplet size of the HIPEs decreased significantly,the Absorbed Protein?AP%?increased,and the Surface Coverage?SC%?decreased,the gel network structure of the HIPEs enhanced,the apparent viscosity of the HIPEs increased,and the freezing points of the HIPEs decreased.The repulsive interaction?including the electrostatic repulsion and space repulsion?between CS and AHSPI at p H 3.0 not only improved Pickering efficiency of AHSPI,but also increased thickness of the interfacial layer between oil droplets,which gives the HIPEs superior freeze-thaw stability.The appearance,microstructure,and viscoelasticity of the HIPEs remained stable after freeze-thaw.And the HIPEs prepared by CS and AHSPI in 1:1 and 1:2were similar to the commercial mayonnaise in terms of average droplet size and rheological property,which could act as mayonnaise-like emulsions to replace mayonnaises.At the same time,the method of using non-covalent interaction provides new ideas for the research of improving the freeze-thaw stability of HIPEs.In summary,the superior particle characteristics of AHSPI were helpful for HIPEs forming stable interfacial layer and strong gel network structure,which was the key for improving freeze-thaw stability.The research results had significant reference value for further exploring the development of the low-cholesterol sauce emulsions with high freeze-thaw stability,and expanded the application of functional plant proteins in emulsion foods.