| Soybean soluble polysaccharide(SSPS)is anionic polysaccharide extracted from the by-product of isolated soy protein production.In this study,a simple and eco-friendly procedure had been developed to prepare high-molecular-weight octenyl succinic esters of SSPS(OSA-SSPS)via the esterification between SSPS and octenyl succinic anhydride(OSA).The storage stability of ASSP/SSPS composite emulsion was firstly investigated and evaluated through studying the effect of the addition of SSPS,heating,ionic strength,as well as p H change on the stabilizing behavior of O/W emulsions prepared from ASSP and SSPS complexes.Besides,during the reaction between SSPS and OSA,the effect of several factors on the properties of SSPS modified products were investigated through single-factor experiments and therefore the suitable OSA-SSPS preparation conditions were determinated.Furthermore,after the novel modified SSPS was gained,characterization measurements and morphology analysis were taken to determine the milk protein stabilization properties of OSA-SSPS to stabilize the milk dispersions in acidic p H conditions as well as emulsifying properties in stabilizing ASSP/OSA-SSPS emulsions.(1)In this research,long time storage stable ASSP/SSPS complex emulsions were produced by means of electrostatic and hydrophobic interactions,high pressure homogenization and heat treatment having a droplet size 263 ± 2 nm.The particles were spherical with strong interfacial films,as evidenced by SEM,TEM,AFM as well as the ?-potential studies.Such emulsions resulted in heating stable dispersions containing corn oil at the concentration of 20.0%,even at the p H around the isoelectric points of ASSP.After 90 days storage at 4 °C,the mean diameter of emulsions after heating at 80 °C for 60 min was 314 ± 1 nm compared with 341 ± 3 nm of emulsions unheated.The heat-stability of dispersions was affected by emulsion conditions,so the present research demonstrates the emulsion stability against heat treatment,ionic strength and p H change.These valuable properties of emulsions prepared from ASSP/SSPS complexes may provide a promising way to deliver the hydrophobic compounds,and then further research will be emphasized on the loading and unloading bioactive substance.(2)The relatively suitable preparation conditions of OSA-SSPS were determined: the proportion of OSA and SSPS was 1:7(w/w),then the OSA was added slowly with stirring and keeping the p H staying in 8.5 for 35 min.The absolute molecular weights of OSA-SSPS and SSPS were 620 k Da and 53 k Da,respectively.OSA-SSPS had some similar properties to SSPS,such as microstructure and viscosity of 1 wt% concentration.(3)Compared to SSPS,OSA-SSPS showed different milk protein stabilization properties.The stabilizing behavior of OSA-SSPS was better than that of SSPS at p H range of 3.8-4.6,and poorer at p H 3.6.The model mixture of OSA-SSPS had smaller particle sizes at p H range of 3.8-4.6 and larger absolute negative charges at p H 2.0-10.0.In addition,from the molecular diameter measured by DLS and AFM image,the surface concentration of OSA-SSPS was larger than that of SSPS,which indicated that the thicker OSA-SSPS layer produces larger steric repulsion to milk protein particles.The mechanism for the greater ability of OSA-SSPS to stabilize milk proteins was proposed on the basis of the results discussed in this research.(4)The emulsions prepared with OSA-SSPS had more monodisperse oil droplets than SSPS in different p H and ionic strength media so the results showed that OSA-SSPS higher emulsifying ability than SSPS.Compared to SSPS,the stabilizing ability of OSA-SSPS was better than that of SSPS and the fixed OSA-SSPS chains in the interfacial films of ASSP/OSA-SSPS emulsions were more able to make the oil droplets stable in aqueous phase even under conditions where ASSP tended to precipitate and electrostatic repulsion exists between ASSP and SSPS molecules. |
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