Construction, stability and photodynamic germicidal efficacy of curcumin nanoemulsion stabilised with Maillard conjugate of Wpi-Rha

Curcumin has excellent antioxidant and antibacterial properties. The poor solubility and easy degradation limit its application. The present investigation was aimed to prepare curcumin nanoemulsions (Cur-Ne), employing homogeneous and ultrasonication for the encapsulation of curcumin to overcome these problems. Cur-Ne stabilised using whey protein isolate and rhamnose conjugate (Wpi-Rha) was prepared by Maillard reaction. Furthermore, the processing ( i.e . ionic strength, heat and freeze-thaw) and storage stability of Cur-Ne were evaluated. Moreover, the bactericidal capacity of Cur-Ne combined with photodynamic therapy (PDT) technology was estimated. Cur-Ne was prepared successfully with the droplet size of 185.97 ± 6.65 nm, polydispersity index (PDI) of 0.21 ± 0.01, zeta potential of −35.17 ± 0.15mV and entrapment efficiency of 97.0 ± 0.07%. Meanwhile, Cur-Ne was stable at different storage and processing conditions. In addition, the DPPH and ABTS radical scavenging rates of Cur-Ne were 84.86 ± 0.24% and 99.63 ± 0.48%, respectively. At the adding amount of 5 μL of Cur-Ne, the Cur-Ne could deactivate the Escherichia coli and Staphylococcus aureus with the antibacterial rate of 99.05 ± 0.13% and 99.11 ± 0.18%, respectively. Curcumin loaded in nanoemulsion and combined with PDT provide new ideas for food storage and sterilisation.