Improving the stability and anti-L. monocytogenes activity of thymol casein nanoparticles by forming eutectic solvent with lauric acid

Thymol forms eutectic solvents with lauric acid under appropriate mixing ratios. These eutectic solvents were shown to have a lower melting point, weaker irritatibility, and stronger antibacterial activity than pure thymol. However, the application of these eutectic solvents is currently limited by their poor water solubility and chemical instability. For this reason, thymol/lauric acid eutectic solvents were loaded into casein nanoparticles (ThyLA-NPs) to improve their solubility and stability characteristics. The physicochemical stability, antibacterial activity, and potential application for meat (pork) preservation of the ThyLA-NPs was then compared to that of thymol casein nanoparticles (Thy-NPs). The results showed that ThyLA-NPs exhibited long-term sustained release, better thermal stability, and better storage stability due to the higher hydrophobicity of the eutectic solvents. Moreover, the ThyLA-NPs showed higher antibacterial activity against L. monocytogenes. The pork preservation study indicated that the ThyLA-NPs were more efficient at inhibiting microbial growth and lipid antioxidation than the Thy-NPs, which extended the shelf life of the pork. These results may promote the application of thymol in the food industry to control food safety and quality.