Dairy Foods: Microbiology

Escherichia coli O157:H7, a leading cause of bacterial food borne disease outbreaks, is responsible for approximately 73,500 cases of foodborne illness per year. Recent research has shown that caffeine has the ability to inhibit DNA repair in bacteria and therefore could be mutagenic compound. The objective of this research was to determine the effectiveness of caffeine on inactivation of (E. coli O157:H7 in Brain Heart Infusion (BHI) broth. Overnight samples of six E. coli O157:H7 strains (E 1730, E 4546, E 0019, Cider, 380 and 944) were used in this study. These strains were inoculated individually at an initial inoculum level of 2 log CFU/ml into BHI broth containing caffeine with different concentrations of 0.0, 0.25, 0.5, 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00%. Samples were then incubated at 37 C for 24hrs. Samples were withdrawn at different time intervals to determine turbidity using spectrophotometer at 575nm. Results revealed that the addition of caffeine inhibited the growth of E. coli. Significant growth inhibition was observed with concentration levels 0.50% and higher. These results indicate that caffeine has potential as an antimicrobial agent and should be investigated further as a food additive to increase the biosafety of consumable food products.