Abstract: 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.

Key words: whey protein isolate, gel, release characteristics, dynamic model