Polymer-cocktail edible aerogel templates for structuring omega-3-rich sardine by-product oil into stable oleogels.
Abstract
Sardine by-product oil is a sustainable marine lipid resource rich in long-chain polyunsaturated fatty acids (PUFAs), yet its high oxidative susceptibility and poor physical stability limit direct food application. An alginate-carboxymethyl cellulose-gelatin-chitosan matrix was developed to structure PUFA-rich oil through sequential hydrogel-aerogel-oleogel transformation. The gelatin-chitosan ratio was systematically varied to modulate network reinforcement and oil immobilization performance. Freeze-drying generated a hierarchical porous aerogel structure, consisting of interconnected macroporous channels formed by ice-templating and nanoscale wall pores detected by nitrogen sorption analysis. The macroporous channels facilitated bulk oil uptake, whereas the wall mesopores enhanced oil-matrix contact and interfacial confinement. Oil absorption capacity ranged from 2.77 to 4.40 g/g, with the gelatin-enriched PC3 system showing the highest oil binding capacity of 80.32%, indicating effective lipid confinement within the aerogel-derived oleogel matrix. Increasing gelatin proportion improved pore uniformity and structural stability. FTIR analysis confirmed hydrogen bonding and electrostatic interactions within the reinforced polysaccharide-protein network. Fatty acid profiling demonstrated preservation of PUFA fractions after structuring. This hierarchical system effectively immobilizes marine oil while maintaining structural integrity, oxidative stability, and nutritional quality for potential food applications.