Structure-network-function engineering of carrageenan edible film for food packaging: A comprehensive review of blend...

Carrageenan (κ/ι/λ) is a seaweed-derived sulfated polysaccharide increasingly used in carrageenan-based edible films and coatings as sustainable alternatives to petroleum-derived packaging. Yet most studies remain formulation-specific, limiting comparability and obscuring how carrageenan type, ionic setting and network architecture jointly determine food-validated performance. This review consolidates carrageenan film systems using a Structure-Network-Function framework. It links κ/ι/λ chemistry and sulfate density to chain conformation and baseline strength-flexibility-gelation behavior and explains how K⁺/Ca²⁺ regulate helix aggregation and junction-zone density, governing humidity-dependent mechanics and oxygen/water-vapor transport. Carrageenan system design routes are synthesized across polymer blends, crosslinking/stabilization and nanocomposites (reinforcement and tortuous diffusion pathways under dispersion-limited thresholds). Functional performance is evaluated within carrageenan active films through additive compatibility and controlled release/immobilization to avoid tensile-strength loss and permeability increases and within carrageenan intelligent films through indicator stabilization and quantitative ΔE calibration to spoilage thresholds (pH, TVB-N, CO₂, microbial load, sensory). Evidence from seafood, meat and produce/dairy applications is integrated to extract practical design rules. Finally, translation bottlenecks RH sensitivity, additive migration/safety acceptance, structure-function trade-offs, scale-up from casting to coating/lamination and non-standard reporting are mapped to a roadmap emphasizing humidity cycling, migration protocols and standardized metrics for reproducible scale-ready carrageenan packaging.