Antimicrobial Activity of Lactic Acid Against Pathogen and Spoilage Microorganisms

Abstract

Preliminary examination of the antimicrobial activity of lactic acid against nine bacteria (Escherichia coli, Proteus mirabilis, Salmonella enteritidis, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Listeria monocytogenes, Bacillus cereus and Bacillus megaterium) and three yeasts (Rhodotorula sp., Saccharomyces cerevisiae and Candida albicans) was performed using disc diffusion and broth microdilution method. At a concentration of 321 mg/mL, inhibition zones ranged from 24.0 mm (Es. coli) to 38.3 mm (En. faecalis) for the tested bacteria. The inhibition zones of the yeasts ranged from 11.3 mm (Sac. cerevisiae) to 14.0 mm (Rhodotorula sp.). Lactic acid minimal inhibitory concentration for bacteria was ≥1.25 mg/mL, while minimal biocide concentration was ≥2.50 mg/mL. Minimal inhibitory concentration for yeasts was ≥12.50 mg/mL, while minimal fungicidal concentration was ≥25.00 mg/mL. The obtained results showed that lactic acid could be used as an efficient natural antimicrobial agent improving the safety of all-natural foods. Practical Applications Consumer perception that synthetic food additives may be associated with potential toxicological problems has recently generated interest for the use of naturally derived compounds in the food industry. The use of lactic acid is considered as a good alternative and may be more acceptable to consumers than synthetic food additives because of its natural origin, potential antimicrobial activity, as well as preservative, antioxidant, flavoring and acidifying properties as well as low cost. For ensuring food safety, combination of lactic acid with other natural antimicrobial agents or other preservation methods should be considered. Therefore, there is a potential for lactic acid usage in the development of eco-friendly technology which ensures food safety.