超声处理大豆分离蛋白与壳聚糖复合物对O/W型乳液稳定性的影响

Effect of Ultrasonic Treatment on Stability of Oil-in-Water(O/W) Emulsion Containing Soybean Protein Isolate-Chitosan Complex

为探究超声处理大豆分离蛋白-壳聚糖(soybean protein isolate-chitosan,SPI-CS)复合物对形成O/W型乳液性质的影响,主要研究了复合物表面疏水性、乳化活性、乳化稳定性与油-水界面张力、乳液粒径、乳液稳定性之间的关系。结果表明:未经超声处理的SPI-CS复合物表面疏水性、乳化活性、乳化稳定性和界面吸附性较低,形成的O/W型乳液粒径相对较大,约100?μm,乳液Zeta电位较低,乳滴有发生聚集的倾向。乳液贮存7 d后乳层析指数最高。经超声处理后SPI-CS复合物形成的乳状液性质发生明显变化,随着超声功率的增加,形成的O/W型乳液的稳定性有所增加:超声功率为400 W时SPI-CS复合物形成的乳液最为稳定,乳层析指数最低;当超声功率超过400 W时,乳液的光学显微镜观察显示其粒径有所增大,同时乳液的Zeta电位、乳化活性和乳化稳定性明显下降,界面张力降低缓慢。超声处理暴露了蛋白质分子的内部结构,使部分结构展开、柔性增加,促进了其与壳聚糖之间的静电相互作用,说明超声处理的大豆分离蛋白与壳聚糖形成的复合物影响了O/W型乳液的稳定性及相关性质。

The purpose of this study was to explore the effect of ultrasonic treatment on the properties of O/W emulsion containing soybean protein isolate-chitosan （SPI-CS） complex. The relationship between surface hydrophobicity, emulsifying activity and emulsion stability and oil-water interfacial tension, particle size and stability of the emulsion were investigated. The results showed that surface hydrophobicity, emulsifying activity, emulsion stability and interfacial adsorption of SPI-CS without ultrasonic treatment were relatively low, and the particle size of the formed O/W emulsion was about 100 μm. The zeta potential of the emulsion was low and the droplets tended to aggregate. Creaming index was the highest after storage for 7 days. Ultrasonic treatment of SPI-CS formed emulsions with markedly improved properties. The O/W emulsion became more stable with increasing ultrasonic power, and it had the highest stability and lowest creaming index at 400 W. However, when the ultrasonic power exceeded 400 W, the particle size of emulsions was increased under light microscope, and zeta potential, emulsifying activity, emulsion stability and interfacial tension decreased obviously. Ultrasonic treatment exposed the internal structure of SPI protein molecules, unfolded part of the protein structure and increased molecular flexibility, thereby promoting the electrostatic interaction between chitosan and the protein, which indicated that ultrasonic-treated SPI-CS could affect the stability and relevant properties of O/W emulsion.