Off-flavor formation in omega-3-rich oils: Mechanisms, volatile markers, and emerging mitigation technologies

Lipid autoxidation of eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3) generates volatile carbonyl compounds-including propanal, hexanal, (E)-2-nonenal, and (E,Z)-2,4-decadienal-that contribute to fishy, rancid, and cardboard-like off-flavors and limit the commercialization of omega-3-enriched foods. Seventy-six percent of the global population fails to meet recommended EPA + DHA intake thresholds, driving demand for stable functional food applications (Calder et al., 2025). This review integrates off-flavor formation chemistry with a comparative assessment of conventional and emerging mitigation strategies across eight performance dimensions. Particular attention is given to the divergence between simplified model lipid systems and commercial fish or microalgal oils, in which minor components-heme-derived iron, transition metals, tocopherols, phospholipids, pigments and residual cellular material-modulate hydroperoxide decomposition and therefore the resulting volatile profile. The frequent assumption that odor activity values (OAVs) are additive is examined against experimental evidence of aroma masking and odorant synergy in marine and algal oils, and the oxidative fishy note is explicitly distinguished from the ammoniacal odor of microbially derived trimethylamine. Among conventional approaches, steam deodorization is industrially mature and effective for volatile removal, although severe thermal conditions may compromise lipid quality and promote the formation of process contaminants. Green extraction technologies-supercritical CO₂, ultrasound-assisted, and enzymatic-assisted extraction-offer reduced oxidative damage during oil production and are gaining industrial relevance (Jamalluddin, Ismail, Ab. Mutalib, & Sikin, 2022). Clean-label interfacial engineering using protein-polyphenol complexes and multilayer emulsification represents an emerging strategy for simultaneous emulsion stabilization and off-flavor suppression (Hennebelle et al., 2024). Emerging non-thermal technologies-ozonation and cold plasma dielectric barrier discharge-offer selective volatile degradation mechanisms but their industrial adoption remains constrained by the absence of clearly established, application-specific regulatory pathways for omega-3 oil deodorization; hybrid cold plasma-antioxidant configurations remain at an early technology readiness level. Matrix-specific mitigation options for microalgal omega-3 oils are summarized separately. A conceptual Precision Oxidation Management (POM) framework is introduced, defining selective volatile degradation, hybrid process architecture, and AI-supported adaptive monitoring as three pillars for industrial translation.