Effect of protein and plasticizer concentrations in film forming solutions on physical properties of edible films based on muscle proteins of a Thai Tilapia

Proteins from fish muscle are biopolymers capable of forming edible films. Thus, the objective of this paper was the study of some physical properties of films produced with the sarcoplasmic and myofibrillar proteins (MP) from Thai Tilapia muscle, as function of the protein and plasticizer concentration in the film-forming solution, thermally treated at 90 °C/30 min. The films were prepared by a casting technique. The filmogenic solutions (FFS) were prepared as follows: 1 or 2 g of protein/100 g of FFS, 15-65 g of glycerin/100 g of protein, pH = 2.7 (acetic acid) and FFS thermal treatment of 90 °C/30 min. These films were characterized for color, opacity, mechanical properties, and viscoelastic properties. Only the films made with 2 g of MP/100 of FFS were characterized for the thermal properties. In general, all properties were affected by the plasticizer concentration. The effect of the protein concentration was observed mainly upon the mechanical properties. The films prepared with 2 g of MP/100 g FFS were more resistant than the others. In a general manner, the films properties were similar of that of myofibrillar fish films excepted the optical properties. The MP films were more colored and opaque than the myofibrillar one.