Tailoring the Properties of Soy Protein-Based Bioplastics via Plasticizer Composition and Extrusion Temperature for Controlled Iron Release

The development of sustainable bioplastic matrices for controlled micronutrient delivery represents a promising strategy in the agri-food and biomedical sectors. This study investigates the influence of plasticizer type (glycerol, water and their mixtures) and processing temperature (70–110 °C) on the fabrication and functional properties of extruded soy protein-based matrices for iron release. Results show that both the nature of the plasticizer and the extrusion temperature critically affect the microstructure and mechanical behavior of the matrices. Specifically, an intermediate glycerol/water ratio (50/50) during extrusion at 90 °C significantly improves matrix resistance, making it optimal for iron-controlled release. These findings underscore the crucial role of formulation and thermal parameters in engineering protein-based delivery systems, thereby paving the way for the design of next-generation biodegradable functional materials.