Glycerol and fatty acid influences on the rheological and technological properties of composite films from residues of Cynoscion acoupa

Abstract

The myofibrillar proteins were characterized using electrophoretic analysis. The rheological analysis was done in the film solutions (FS) and in the composite films, which were evaluated using technological properties, thermogravimetry, x-ray diffraction, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The Herschel-Bulkley and Bingham models described the dilating fluid behavior for FS, and the addition of fatty acids (FA) (stearic and palmitic) and glycerol significantly increased the viscosity of FS. Films produced with 1% myofibrillar fish proteins with 5% of PE (stearic), PP (palmitic) and PC (caproic) acids showed greater brightness, were thinner (0.02 mm each), lower water vapor permeability (PE = 1.94, PP = 1.71 and PC = 2.12 g mm/m2.d.kPa), and films were less soluble (PE = 13.9, PP = 13.3 and PC = 21.6%); had better visible light barrier properties (p ≤ 0.05) compared to films with glycerol. The films with stearic and palmitic acids (PE and PP) showed a more ordered structure (crystalline) and better thermal resistance when compared to other films. The films with the (FA) PE, PP and PC showed greater hydrophobic interactions with FTIR due to the displacement of the amide-A band and greater amplitude the amide II band. The addition of glycerol in the films increased the roughness as seen with SEM. The addition of FA contributed positively to the technological properties of fish proteins films that might be used as food packaging.