Purpose: The objectives of this study were: (1) to evaluate the antimicrobial efficacy of ethyl alcohol, propylene glycol, and triacetin on the survival of Salmonella spp., E. coli O157:H7, S. aureus, and L. monocytogenes, (2) to find the optimum concentration of each carrier compound that may be bactericidal (ex: 5-log reduction) for vegetative pathogens.
Methods: Cultures (1 ml) of S. Typhimurium, E. coli O157:H7, S. aureus, and L. monocytogenes were added to 9 ml of nutrient broth with ethyl alcohol at concentrations of 7.5, 10.0, and 12.5 % and 15, 20, and 30% for propylene glycol to achieve an initial inoculation of 6-7 log CFU/ml. For triacetin, all the cultures were inoculated in dry form (1 g) to 9 ml of triacetin at concentrations 75, 80, and 85% to achieve an initial inoculation of 6-7 log CFU/ml. All the experiments were performed in duplicates. The samples were stored at ambient temperature. Microbiological analysis was performed following 0, 1, 3, 7, 14, 21, and 31 days of storage.
Results: Results indicated that the bactericidal effect was due to the combination of concentration and storage time. The optimum bactericidal concentrations that caused a 5-log reduction (P < 0.05) in vegetative pathogens were 12.5% for ethyl alcohol, 20.0 or 30.0% for propylene glycol, and 75% for triacetin.
Significance: The current study provides scientific basis for the antimicrobial effect of different chemical carrier compounds routinely used in food flavor systems.