大豆分离蛋白-壳聚糖复合物的形成机理研究

Study on the Formation Mechanism of Soy Protein Isolate-Chitosan Complex

为探究蛋白质与多糖之间的相互作用,以大豆分离蛋白(SPI)-壳聚糖(CS)复合体系为研究对象,采用浊度法、电位分析、粒径分析、黏度测定及等温滴定量热法研究两者间的复合物形成状态、机理以及复合过程中的热量变化。结果表明,当pH值为3.0时,不同复合比对SPI-CS复合溶液的浊度影响不大;当CS浓度大于SPI浓度且SPI/CS复合比为1∶30时,复合溶液的粒径分布出现明显的两个峰,电位值变化不大,且两者之间的静电相互作用力微弱,几乎无热量变化。当pH值为6.0时,SPI-CS复合溶液浊度值升高,并在SPI/CS复合比为1∶10时CS达到饱和,此时复合溶液的电位值由原来的负值变为正值,两者间由于静电相互作用形成复合物使得平均粒径分布明显增大;等温滴定量热法研究结果表明,SPI和CS之间的相互作用为放热反应(ΔH<0)。本研究为蛋白质和多糖在食品工业等领域的应用提供了理论依据。

In order to understand the interaction mechanism between protein and polysaccharide,soybean protein isolate（ SPI）-chitosan（ CS） system was chosen as the research object,and turbidity,potential analysis,particle size analysis,viscosity measurement and isothermal titration calorimetry（ ITC） were used to study the state and mechanism of the complex formation and the heat change in the interaction process between the two kinds of compounds. The results showed that compound ratio had no significant effect on the turbidity of SPI-CS mixed solution at pH value 3. 0 and two peaks appeared in the particle size distribution of mixed solution（ SPI/CS = 1 ∶ 30）. In addition,the potential of the SPI-CS mixed solution changed slightly at pH value 3. 0,resulting in the weak electrostatic interaction and almost no heat change between SPI and CS. At pH value 6. 0,the turbidity of SPI-CS mixed solution increased and saturated at 1∶ 10 of the SPI/CS ratio. The potential of the mixed solution turned to positive from the original negative and the average particle sizes of SPI-CS complexes increased significantly due to by electrostatic interaction. The results of ITC showed that the interaction between SPI and CS was exothermic reaction（ ΔH〈 0）. This study provided a theoretical basis for the application of protein and polysaccharide in food industry.