The effect of mono and polyglycerol laurate on spoilage and pathogenic bacteria associated with foods

The antibacterial activity of monolaurin and triglycerol 1, 2 laurate alone and combined with three different chelating agents, at different pH (7, 6, 5.5 and 5), different NaCl concentrations (0.5 to 7%) and various combinations of pH and NaCl concentrations was investigated. The activity of these agents against 16 bacteria (7 Gram-positive and 9 Gram-negative) was studied using the spiral gradient end point test to determine the minimum inhibitory concentration (MIC). Monolaurin was effective against all the Gram-positive bacteria studied, but it as only effective against the Gram-negative bacteria in the presence of EDTA. The inhibition was greatest at low pH and high NaCl concentrations. Concern has been expressed about the use of monolaurin in foods because of its poor solubility. Polyglycerol esters are more soluble and antimicrobial activity of these compounds has been observed. Triglycerol 1,2 laurate exerted some inhibitory effects, but was not as inhibitory as monolaurin even in the presence of the chelating agent and under conditions of low pH and high NaCl levels. Other chelators investigated (monoglyceride citrate and sodium citrate) did not promote the inhibitory effect of monolaurin