Super antioxidant and high antibacterial ability bi-functional xylitol/2-hydroxypropyl-β-cyclodextrin carbon dots with hydroxyl-functionalized for rainbow trout preservation.

In 2020, Rainbow trout production reached 959,600 tons, representing 4 % of the global trout output. However, microbial contamination and lipid and protein oxidation spoil around 15 % of total aquatic products. Traditional food preservatives, used for their antibacterial or antioxidant properties, often fall short due to the disparity between the radical-scavenging ability of antioxidants and the ROS-generating capability of antimicrobial agents. This study developed bifunctional xylitol-based carbon dots (xβ-CDs) using 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD), which exhibited both super antioxidant and high antibacterial activities. The incorporation of xylitol into xβ-CDs substantially enhanced their functional performance. The xβ-CDs displaying remarkable inhibition of DPPH (1-Diphenyl-2-trinitrophenylhydrazine), ABTS (2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate), and ·OH radicals (96.31 %, 99.74 %, and 99.72 %, respectively), rivaling the antioxidant capacity of vitamin C (VC). The xβ-CDs also effectively combated spoilage bacteria by compromising the cell wall and membrane integrity, reducing total protein, AKP, and ATP enzyme levels by 51.25 %, 70.08 %, and 57.80 %, respectively. Moreover, storage tests revealed that xβ-CDs extended the shelf life of Rainbow trout fillets by 3 days. These results indicate that xylitol/2-hydroxypropyl-β-cyclodextrin carbon dots offer a promising approach to preventing bacterial infections, protein oxidation, and lipid oxidation in rainbow trout.