乳清分离蛋白凝胶VC释放过程的动力学

本研究以VC作为食品功能性成分模型,利用热诱导使其封装于乳清分离蛋白(whey protein isolate,WPI)凝胶内,通过静态释放实验和动力学分析,探讨释放介质pH值、温度、载药量、释放液离子浓度对WPI凝胶中VC释放特性的影响,并建立VC在WPI凝胶中释放过程的动力学模型。实验结果表明,VC在WPI凝胶中累计释放分数的变化与蔗糖的动力学模型不同,不遵循已有的Korsmeyer-Peppas模型X=Kt~n,而遵循本研究建立的修正模型:X=Kt~ne~(-k’t),且相关系数R2在0.95~0.99之间。VC的释放速率,随pH值、温度以及释放液离子浓度的增加不断增大,随载药量的增加而不断减小。研究表明,WPI凝胶具有环境应答性,以其为载体的VC释放过程受环境的pH值、温度、释放液离子浓度等因素影响。因此,通过调节释放体系的pH值、温度、载药量、释放液离子浓度可以达到控制VC释放的目的。

Release Kinetics of Ascorbic Acid from Whey Protein Isolate Gel

In this paper, VC was entrapped as a model functional food ingredient into thermally induced whey protein isolate (WPI) gels and then subjected to static release experiments and kinetic analysis in order to investigate the influence of release medium (phosphate buffer) pH and concentration, temperature and drug loading on VC release characteristics and to establish a kinetic model to describe the release process. The results showed that the change in the cumulative release rate of vitamin C from whey protein gels was different from that of sucrose, with the former observed to not follow the Korsmeyer Peppas model X = Ktn instead follow the modified model presented in this study X = Ktne-k’t with a correlation coefficient R2 in the range of 0.95–0.99. The release rate of vitamin C increased with the increase in pH value, temperature and buffer concentration, and decreased with the increase in drug loading. Whey protein isolate gels could respond to the environment, and the release process of ascorbic acid was influenced by pH, temperature, drug loading, medium concentration and other factors. Thus the VC release from the carrier could be controlled by adjusting release medium pH and concentration, temperature and drug loading.