Modeling of Swelling in Whey Protein Based Gel Systems

M.H. Oztop, and K.L. McCarthy
University of California, Davis, CA, USA

In this study, Whey Protein Isolate (WPI) gels of different thickness were soaked in solutions of pH 7.0 and mass uptake was recorded. A finite element model based on diffusion and deformed mesh application modes in COMSOL Multiphysics was developed. Deformed mesh application mode provided the opportunity to incorporate the moving boundaries. The moving boundaries were solved by introducing integration coupling variables. In order to estimate the diffusion coefficient, D (m2/s), a MATLAB m file called COMSOL and the results of the COMSOL run were combined with the MATLAB function (‘fminsearch’). The model fit well with experimental results (R2>0.95) and enabled estimation of diffusion coefficients. Diffusion coefficient of water in the WPI gels was found to be 3.25e-10 m2/s and independent of gel thickness. The experimental and predicted dimensions of the gels were also found to be similar. The model can be extended for different geometries and be used for prediction purposes for designing new release systems.