BACKGROUND: Fish spoils quickly due to oxidation, microbial activity, and high moisture content. Therefore, natural preservatives such as saffron (Crocus sativus L.) nanoemulsions have the potential to extend the shelf life of seafood while reducing the use of synthetic preservatives.

OBJECTIVES: This study evaluated the effectiveness of saffron (Crocus sativus L.) nanoemulsions (SNE1–SNE8), via spontaneous or ultrasonic emulsification, in extending the shelf life of rainbow trout and enhancing antioxidant effects.

METHODS: Saffron nanoemulsions were characterized using Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR), and their physical stability was monitored for 28 days. Eight nanoemulsion formulations were initially prepared and characterized; however, only SNE1–SNE4 were subsequently evaluated in the rainbow trout preservation study. Rainbow trout fillets coated with SNE1–SNE4 were stored at 4°C and 8°C for 21 days. Total volatile basic nitrogen, peroxide value, thiobarbituric acid, pH, antioxidant activity, and sensory properties were compared with those of uncoated fillets and fillets treated with pure saffron extract.

RESULTS: DLS and TEM demonstrated that the saffron nanoemulsions exhibited spherical and homogeneous droplets with particle sizes ranging from 9.7 to 22.3 nm, while SNE4 (10.6 nm) showed the highest physical stability during 28 days of storage (P < 0.05). FTIR confirmed the preservation of the characteristic functional groups of saffron following nanoemulsion formation. During refrigerated storage, biochemical parameters differed significantly among the treatments (P < 0.05). After 21 days at 4°C, Treatment d (SNE4) showed the lowest TVB-N (27.16 ± 0.28 mg/100 g), PV (0.40 ± 0.002 meq O₂/kg), TBA (0.54 ± 0.008 mg MDA/kg), and pH (6.45 ± 0.02), while maintaining the highest overall sensory acceptance.

CONCLUSIONS: Saffron nanoemulsions effectively preserved rainbow trout by delaying protein degradation and lipid oxidation while maintaining sensory quality during refrigerated storage (P < 0.05). These findings highlight their potential as natural alternatives to synthetic preservatives for seafood preservation.