Investigation of Physicochemical, Antioxidant, and Antimicrobial Properties of Thymol and Resveratrol Encapsulated with Zein-Caseinate Nanoparticle

Thymol and resveratrol are organic, phenolic compounds with wide-ranging potential applications in the food industry, mainly use as an anti-oxidation and antibacterial additives. However, their weak stability, low water solubility, and bioavailability have severely limited their industrial applications. Herein, zein-casein nanoparticles loaded with thymol and resveratrol have been successfully prepared using the liquid-liquid dispersion method to empower their stability, solubility, antioxidant, and antimicrobial properties. As a result, formulation of 75% thymol with 25% resveratrol mixing ratio 1:20 (75T25R20) was the most stable nanoparticle with zeta potential of -19.54 compared to only thymol or resveratrol nanocapsules (100T0R20 and 0T100R20) with zeta potential of -1.22 and -4.12 respectively.  In addition, scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical activity increased to 58.77% in 75T25R10 nanocapsule compared to the antioxidant activity of nanocapsule of only thymol or resveratrol with DPPH of 20.33% and 13.67% respectively. The synergic effect of the thymol and resveratrol also improved the antimicrobial activity. For example, Minimum Inhibitory Concentration (MIC) against e.coli bacteria in culture medium, drops from 300-350 for sole thymol/resveratrol nanocampule (100T0R10, 0T100R10) to 100 for 75T25R10. Finally, Scanning Electron Microscopy (SEM), and Fourier Transforms InfraRed (FT-IR) spectroscopy have been used for the physical characterization of the resultant NanoParticles (NPs). It is worth mentioning that formed zein-casein nanoparticles loaded with thymol and resveratrol have good redispersibility and physical stability stored at -20 0C. Therefore, this investigation introduces an excellent organic candidate for delivering hydrophobic active compounds, which is of significance in the cosmetics and especially food industries.