Challenges of Alginate-Based Cast Films in Plastic-Free Food Packaging Applications: An Overview

This review investigates the potential of sodium alginate, a biobased polysaccharide from brown algae, for food packaging applications. It analyzes the main challenges of cast films, including water vapor permeability, mechanical performance, and processability, and evaluates strategies to enhance these properties without chemical modification. Chemical modification is excluded because it would classify alginate as a plastic under EU regulations (PPWR, SUPD), conflicting with plastic-free packaging. The review synthesizes literature from 2004 to 2025 on pure sodium alginate films that are plasticized and ionically crosslinked without additional modifiers or nanofillers. While alginate provides excellent oxygen and fat barriers, its high water vapor permeability and brittleness limit broader use. Ionic crosslinking improves strength and water resistance, yet non-uniform networks remain a key challenge. Film performance is also influenced by drying temperature, mixing speed, molecular weight, and protein incorporation. This review differs from previous studies by highlighting the coupled effects of plasticization, ionic crosslinking, and processing limitations that together determine alginate's industrial feasibility. Research gaps concern long-term stability and behavior under industrial packaging conditions. Given environmental and regulatory pressures to replace fossil-based plastics, sodium alginate shows strong potential as a scalable, renewable material for sustainable food packaging.