Beyond Deiodination: A Multifunctional Aerogel for Selective Iodide Removal and Quality Preservation in Nutrient-Rich Algae Extracts

The selective removal of iodide (I–) from nutrient-rich algae extracts remains challenging due to matrix interference. This study evaluated a ε-polylysine-functionalized aerogel (PL-GA) for I– adsorption from two concentrated extracts: Saccharina japonica juice (Sjj) and algae residue juice (Arj). PL-GA effectively adsorbed I–, although its efficiency was modulated by specific kelp biomacromolecules. FT-IR, XRD, and SEM-EDS analyses confirmed I– uptake and associated structural changes. Importantly, PL-GA exhibited high selectivity, preserving most hydrolyzed amino acids, volatile flavors, and antioxidant activity. Sensory analysis indicated minimal changes: a slight reduction in umami and saltiness in Sjj, and a beneficial decrease in bitterness in Arj. Additionally, PL-GA demonstrated inherent broad-spectrum antibacterial activity. These results establish PL-GA as a multifunctional adsorbent for targeted I– removal, which largely maintains the nutritional and sensory profile of algae products while adding a preservation benefit, highlighting its strong potential for application in safer seaweed-based food processing.