Antimicrobial activity of ethanol, glycerol monolaurate or lactic acid against Listeria monocytogenes.
Minimal inhibitory concentrations (MIC) and antimicrobial effects of glycerol monolaurate (monolaurin), ethanol and lactic acid, either alone or in combination, against Listeria monocytogenes in tryptic soy broth were determined. Ethanol at concentrations up to 1.25% did not inhibit growth, but growth was strongly inhibited in the presence of 5% ethanol. MIC values of monolaurin and ethanol alone were 10 micrograms/ml (0.001%) and 50,000 micrograms/ml (5%), respectively. However, MIC values were not changed when monolaurin was combined with ethanol. When 5 micrograms/ml monolaurin was combined with 5% ethanol, the inhibitory effect of the combination was similar to the most active compound alone after 24 h incubation. These data indicate little interaction between monolaurin and ethanol against L. monocytogenes. MIC value of lactic acid alone was 5000 micrograms/ml (0.5%), but was lower when 1.25% ethanol was combined with 0.25% lactic acid. When 2.5% ethanol was combined with 0.25% lactic acid, the combination did not increase the inhibitory effect of the most active single compound alone. This result also indicates that there was little interaction between ethanol and lactic acid.
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Department of Food Science, Louisiana Agricultural Experiment Station, Lousiana State University Agricultural Center, Baton Rouge 70803.
Marshall
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D003470:Culture Media; D004357:Drug Synergism; D000431:Ethanol / Q000494:pharmacology*; D005516:Food Microbiology; D005520:Food Preservatives / Q000494:pharmacology*; D005989:Glycerides / Q000494:pharmacology*; D007773:Lactates / Q000494:pharmacology*; D019344:Lactic Acid; D007848:Laurates / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D050178:Monoglycerides
D003470:Culture Media; D005520:Food Preservatives; D005989:Glycerides; D007773:Lactates; D007848:Laurates; D050178:Monoglycerides; C020777:monolaurin; D019344:Lactic Acid; D000431:Ethanol