Antimicrobial effect of food-grade GML microemulsions against Staphylococcus aureus

Food-grade GML (Glycerol Monolaurate, the glycerol monoester of lauric acid) microemulsions based on multi-component mixtures and enhanced antimicrobial effects have been studied. The compositions included water, GML, several surfactants (ethoxylated sorbitan esters, sucrose esters), alcohols (pentanol and dodecanol), salt (potassium sorbate). The influence of surfactants, alcohols and salt on the phase behavior is discussed in this paper. Four improved formulations of microemulsion systems with large O/W regions have been obtained and demonstrated the enhanced antimicrobial activities against Staphylococcus aureus, compared to Glycerol Monolaurate. Subsequently, one formulation with the highest antimicrobial activity was further studied with respect to the influence of each component on the antimicrobial effect. The results showed that among all the components, GML had the significantly highest (P < 0.01) inhibition ratio 63.52% and played a dominating role in the antimicrobial activities. Therefore, it was concluded that food-grade GML microemulsions had enhanced antimicrobial activities against S. aureus, with a major contribution of GML.