Preparation,Characteristic And Application Of High Internal Phase Emulsion Stabilized By Soybean Protein Isolate

Many high internal phase emulsions type foods are widely consumed,such as mayonnaise,but it can cause the total amount of human serum cholesterol increasing and easy to microbial spoilage.Freezing can stabilize quality and improve shelf life of emulsion type foods,but prone to generate destabilization in this process.In this paper,soybean protein isolate,which known as “blood vessel scavenger”,was used as emulsifier to stabilize high internal phase emulsions(HIPEs),we studied its physicochemical properties and freeze-thaw stability.This research aiming to develop a kind of mayonnaise which has health safety,nutritional value and high freeze-thaw stability,in order to provide some reference for its industrial production.Firstly,using soybean oil as internal phase,we compared the HIPEs characteristics stabilized by soybean protein isolate(SPI)and heat-induced soybean protein isolate(HSPI)and found that HSPI,as Pickering stabilizer,has larger protein particle size,lower zeta-potential absolute and higher surface hydrophobicity;lower protein concentration(c)required to stabilize HIPEs,smaller oil droplet size and higher emulsifying efficiency.HIPEs stabilized by HSPI showed good storage stability,its oil fraction(?)can up to 0.86;with the increasing of c and ?,its oil droplet size decreased and gel network structure got enhanced;two kinds of bridging flocculation structures was formed at low protein and high protein concentrations: single layer particles and aggregate particles between oil droplets,respectively.Then,using heat-induced soy protein isolate at pH 3.0(AHSPI,c=1.0 wt%)as emulisifier,freeze-thaw stability of HIPEs was investigated at different ionic strength(I).With the increasing of I,zeta-potential of AHSPI decreased firstly and then remained basically unchanged;the protein particle size was closely correlate with oil droplet size,both were unchanged firstly and then significantly increased;the yield stress and the resistance to deformation ability of HIPEs increased.HIPEs showed good freeze-thaw stability when I?100 mM,which may be related to freezing point decreasing and viscoelasticity enhancing.Finally,at I=100 mM,high concentration AHSPI(c=6.0 wt%,pH=3.0)and wet egg yolk were used as emulsifiers to stabilize simulated mayonnaise and explored its freeze-thaw stability at different AHSPI substitution ratios.With the increasing of substitution ratio,its color changed from light yellow to white;the freeze-thaw stability of simulated mayonnaise was good only when the substitution ratio was 100%.It may be due to egg yolk competing with AHSPI for adsorption,causing AHSPI desorbed from oil-water interface in freeze-thaw cycles,while the fat crystallization is easy to break through the interface membrane formed by yolk components,resulting in a wide range of condensation and demulsification.