Gelatins derived from aronia-supplemented fish diets: Structural effect and molecular simulation

Fish gelatin, a sustainable substitute for mammalian gelatin, frequently exhibits weaker gel strength and thermal stability, limiting its industrial uses. This study investigated an in vivo method to improve functional characteristics by supplementing Nile tilapia diets with Aronia extract. The control diet (A0) contained no Aronia extract, while the remaining four diets consisted of commercial pelleted feed enriched with 250 mg/kg (A250), 500 mg/kg (A500), 750 mg/kg (A750), and 1000 mg/kg (A1000) of Aronia extract. The gelatin samples revealed thermo-reversible behavior with increasing temperature. A250 exhibited the highest melting temperature of 29.65 °C, compared to 27.43 °C for A0. The gelation temperature for A250 was 17.56 °C, indicating a relatively stable gelatin structure. The elastic modulus (G') was the highest in A250, suggesting an improved gel network compared to the other samples. The gelation rate constant (k_gel) was highest in A250 (540.67 Pa), followed by A750 (447.32 Pa), A500 (393.85 Pa), and A1000 (370.97 Pa), compared to 391.15 Pa for A0. The gel strength was improved, with A250 showing the highest value at 133.9 g, followed by A750, A1000, and A500, while A0 was 102.1 g. The glass transition temperatures (Tg) for A250, fish gelatin (FG), bovine gelatin (BG), and A0 were 76.72 °C, 74.31 °C, 70.71 °C, and 73.52 °C, respectively. Molecular docking studies revealed strong binding interactions between A250 and phenolic compounds, which contributed to the observed structural enhancements. These findings suggest that supplementing fish diets with Aronia extract can substantially enhance gelatin quality, offering a promising alternative to traditional gelatin sources.