Nanoemulsions and Nanostructured Lipid Carriers Containing Polyunsaturated Fatty Acids and Peptides from Mullet...

The high susceptibility of polyunsaturated fatty acids (PUFAs) to oxidation limits their application in food systems, creating the need for strategies that improve stability while preserving bioactivity. This study aimed to extract mullet (Mugil liza) oil by enzymatic hydrolysis, concentrate PUFAs via urea complexation, and develop lipid-based delivery systems to enhance oxidative stability and antioxidant functionality. The extracted oil contained 69% unsaturated fatty acids and remained stable for 12 months (5.91 ± 0.01 mg malondialdehyde/kg). PUFA concentration doubled the levels of eicosapentaenoic acid (EPA, 8.15 ± 0.11%) and docosahexaenoic acid (DHA, 2.64 ± 0.02%). To overcome oxidative instability, nanoemulsions (NE) and nanostructured lipid carriers (NLCs) were formulated using cocoa butter, mullet unsaturated fatty acids, Tween 80, and mullet-derived peptides, which were incorporated as natural antioxidant agents. The systems were characterized for particle size, polydispersity index (PDI), color, pH, morphology, and antioxidant capacity. NLCs exhibited particle sizes ranging from 168.3 ± 2.7 to 405.9 ± 2.8 nm and PDI values between 0.205 ± 0.06 and 0.301 ± 0.02. Formulations containing 3% peptides showed the highest ABTS⁺ (59.20-66.70%) and DPPH (28.90-38.58%) radical scavenging activities. This integrated approach, combining PUFA concentration and peptide-based nanoencapsulation from the same raw material, represents an innovative and sustainable strategy to improve stability, bioactivity, and applicability of fish-derived compounds in functional food formulations.