The study focused on the elaboration and the characterization of blend biofilms based on European eel skin gelatin (ESG) and protein isolate (EPI) and the assessment of European oil (EO) incorporation effect on their properties. Data displayed that the incorporation of EPI and EO to the gelatin formulation decreased the lightness and yellowness of composite and emulsified films, respectively, compared to ESG film. Moreover, ESG films exhibited improved mechanical properties than EPI films. FTIR analysis, all incorporated films with EO at the ratio 1:4 (oil/polymer) revealed similar characteristic bands as in free-oil films. Further, the SEM images of 100% ESG and 100% EPI films showed a smooth and homogenous structure, whereas the cross-section of blend film (at a ratio 50:50) displayed a rougher microstructure. In addition, emulsified film ESG100 revealed a smooth and homogeneous microstructure compared to that prepared using EPI/ESG 50/50 ratio. Furthermore, EPI or EO addition into the ESG matrix enhanced the blend films antioxidant activities.

Aims: This study aimed to investigate the gelation capacity of European Eel Protein Isolate (EPI) through the development of novel emulsion protein isolate-based gels (EPIGs). Furthermore, the research evaluated the extent to which fortification with bioactive European eel oil (EO) modulates the structural and functional attributes of these acid-induced gel matrices. Methods: EPIGs were synthesized via thermal treatment (90°C for 60 min) of EPI solubilized in 20% (v/v) acetic acid, followed by emulsification with EO at two distinct weight ratios: 1:2 and 1:4 (EO:EPI, w/w). The resulting gel structures were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), texture profile analysis (TPA), and scanning electron microscopy (SEM). Results: A 4% (w/v) EPI solution in acetic acid achieved gelation at 54°C, demonstrating superior thermal stability and significant gelling potential. FTIR analysis confirmed the successful incorporation of EO into the gel matrix, while TGA results indicated a slight increase in thermal degradation onset temperatures associated with higher EO concentrations, increasing from 375°C (EPIG1:4) to 382°C (EPIG1:2). Texture analysis revealed that incorporation of EO modestly augmented gel elasticity (from 12.93 mm to 13.19 mm), a phenomenon attributed to the stabilizing interactions between the lipid droplets and the protein network. Microstructural appraisal via SEM indicated that a higher EO load (EPIG1:2) induced the formation of larger pores, whereas the EPIG1:4 formulation exhibited a more cohesive and compact architecture with reduced porosity. Keywords: European Eel; Emulsion Protein Isolate-based Gel; FTIR; Thermogravimetric; SEM.