Species-dependent gelation mechanisms in traditional fish-based pempek: A multiscale FTIR–SEM–EDS study

Abstract

Food systems in pempek have a unique fish-based gel whose properties represent cultural and technological versatility. This research aimed to understand how the multiscale structure and composition of pempek, a traditional Indonesian fish (Channa striata)-based gel, are influenced by fish species. It elucidated the hierarchical relationships linking ionic balance, protein secondary structure, and microstructural architecture that determine gel texture and stability using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The multiscale structure of pempek involved spectral deconvolution of amide bands to quantify protein conformations, morphometric analysis of gel microstructure, and elemental mapping to evaluate ionic composition. Channa striata (snakehead) pempek exhibited β-sheet (44.1%) enrichment, higher Amide I/II ratios (1.28 ± 0.05), lower CH₂ ratios (1.32 ± 0.09), and a compact microstructure with thicker walls and lower porosity. In contrast, Scomberomorus commerson (mackerel) pempek displayed higher α-helix content (32.7%), increased lipid mobility (1.49 ± 0.08), and more open, porous networks. The Na/Cl atomic ratio was higher in snakehead samples, suggesting enhanced electrostatic stabilization and network cohesion. Correlation analysis confirmed a strong interdependence among ionic, molecular, and structural parameters, establishing a hierarchical mechanism from ionic milieu to gel microarchitecture. This study provides new mechanistic insights into species-specific gel formation and validates the FTIR–SEM–EDS framework as a powerful tool for understanding protein gelation, product authentication, and structural design. The research advances food material science by offering a reproducible, multiscale analytical model for optimizing texture, stability, and authenticity in traditional and modern protein-based food systems.