Decoding a novel green and effective antimicrobial agent: Glycerol monolaurate stable in nanosystem

Food microbiological control is the key to protecting food quality. However, glycerol monolaurate (GML), as a generally recognized safe antimicrobial agent, limits its antibacterial activity due to its poor water solubility. Ultrasound-assisted construction of essential oil nanosystems is an ingenious way to solve the above problems. In this study, essential oil-based nanoemulsions (NEs) were constructed by replacing traditional oil phase with tea tree essential oil (TTO) stabilized GML and enhanced antibacterial properties. The results demonstrated that uniform droplets could only be formed when the GML content in the nanosystem was below 50 mg/mL. NEs showed favorable optical properties with a turbidity below 0.1 and a whiteness index below 35, and they were Newtonian fluids (viscosity <0.005 Pa s). Besides, the nanosystem exhibited excellent stability even at extreme pH (1 or 11) and high salt ion concentration (500 mM), where droplet sizes of above system were still less than 100 nm after 15 d. Notably, GML alone cannot exert effective antibacterial effects against E. coli and S. aureus, whereas the encapsulation of GML into the nanosystem allowed it to exert antibacterial activity successfully. Banana was selected to validate the availability of NEs, and the treated groups maintained their attractive appearances and quality after 20 d. Overall, this work developed a new nanosystem to stabilize GML, allowing it to exert antimicrobial activity effectively.