Porous hydrogels from modified starch and cellulose: reactive extrusion processing and functional performance for safe and resilient agri-food systems

Access to safe food is fundamental to human health, creating a growing demand for efficient methods to detect hazardous substances in the food supply. Hydrogels, with their three-dimensional polymeric networks, offer unique advantages such as high surface area, facile functionalization, excellent biocompatibility, flexibility, and mechanical stability. In recent years, stimulus-responsive hydrogels have attracted increasing attention in sensing applications, particularly for food safety monitoring. Biopolymeric hydrogels represent a versatile and sustainable class of materials with broad potential in agriculture, food packaging, controlled drug delivery, and biosensing. In this study, biodegradable hydrogels were produced from modified starch (MS) and native starch (S), modified cellulose (MC), unmodified cellulose (C), gelatin, and glycerol using reactive extrusion (REX), and their structure–function relationships were investigated with emphasis on properties relevant to agri-food systems. Four formulations were fabricated and characterized in terms of porosity, open-pore fraction, thermal stability, moisture sorption, and pH-dependent swelling. Among them, the S.MS-MC-G formulation showed the highest porosity (45.34%), the greatest proportion of open pores (39.81%), and the maximum swelling degree (607% at pH 7). FT-IR confirmed ester and phosphate crosslinking, while TGA demonstrated stability up to ~ 300 °C. Moisture sorption analysis indicated that citric-acid modification reduced the number of primary water-binding sites. The combined microstructural and functional results demonstrate that REX enables the production of stable, highly absorbent biopolymeric hydrogels with properties of interest for water management, moisture modulation, and crop-resilience strategies that can indirectly support food security. Their porous architecture and high swelling capacity also make them strong candidates for future integration into active or moisture-responsive agri-food materials.