Investigation of damask rose extract nanoemulsions as a shelf-life extender for refrigerated beluga sturgeon fillets

This study investigated the potential of damask rose (Rosa damascena Mill. L.) extract nanoemulsions as a natural preservative for Beluga sturgeon fillets during refrigerated storage. Nanoemulsions were prepared using both ultrasonic and maceration methods, and their impact on the physicochemical and microbial properties of the fillets was evaluated. The antimicrobial and antioxidant activities of the extract and nanoemulsions were also assessed. Fillets were coated with zedo gum containing varying concentrations (0%, 1%, 2%, 3%) of the damask rose extract nanoemulsion. These treatments were compared to an uncoated control and a zedo gum-only coating. The results demonstrated that the ultrasonic method yielded the highest extraction efficiency. The nanoemulsions themselves exhibited the strongest antioxidant activity as measured by the IC50% value. Following storage under refrigeration, analyses revealed increases in the amount of nanoemulsion, pH, total volatile nitrogen (TVB-N), thiobarbituric acid (TBA) index, and L* color value (lightness) in the sturgeon fillets. Additionally, an increase was observed in the total number of viable mesophilic and psychotrophic bacteria, H₂S-producing bacteria, lactic acid bacteria, and coliform bacteria. However, the color components a* (redness) and b* (yellowness) along with sensory properties improved in the sturgeon fillets. Based on these findings, sample 5 (3% nanoemulsion-zedo gum coating) emerged as the superior treatment. This treatment demonstrated the most significant reduction in microbial load while maintaining or enhancing sensory attributes, suggesting its potential to extend the shelf life of Beluga sturgeon fillets during refrigerated storage.