Rheological model for the mechanical properties of myofibrillar protein-based films

A phenomenological rheological model was developed to describe the molecular interactions and predict the mechanical properties of fish myofibrillar protein-based films, irrespective of their thickness. The model was built of a parallel array of Maxwell and elastic elements in which a fracture element was introduced. The total number of parallel branches was directly correlated with the most characteristic dimension of the samples, i.e., the film thickness. The rheological parameters (alpha, elastic modulus, and viscosity coefficient) were determined from numerous experimental data sets and appeared to be independent of thickness. They could be used to characterize the molecular interactions in the films. These parameters were only sensitive to the type of data used for calculations (force-deformation, relaxation, or creep) and to the range of experimental conditions applied to obtain these data. The model successfully predicted force-deformation-time relationships for these biopolymer-based films.