Survival and Growth of Escherichia coli O157:H7 in the Presence of Caffeine and Cinnamon

Introduction: Escherichia coli O157:H7 has emerged with increasing frequency as a foodborne pathogen of concern, which causes hemorrhagic colitis and hemolytic uremic syndrome.  Caffeine and cinnamon have shown to exert strong antimicrobial effects against E. coli O157:H7. This suggests the potential use of caffeine in combination with cinnamon in the food industry for enhancement of safety.

Purpose: The objective of this study was to investigate the effect of caffeine and cinnamon against E. coli O157:H7 in laboratory medium.

Methods: Tryptic Soy Broth (TSB) was prepared with caffeine (Ca 0, 0.3, 0.4, and 0.5%, w/v), cinnamon (Ci 0.3 and 0.5%, w/v) and combination of Ca 0.4 %, w/v and Ci 0.5%, w/v. Three strains of E. coli O157:H7 were individually inoculated (approximately 3.00 log CFU/ml) into each sample and incubated at 37 °C for 48 hr. At the end of the incubation period, samples were analyzed for bacterial population.

Results: At 0.3, 0.4%, and 0.5%, Ca decreased the bacterial population by 1.54, 3.0, and 4.0 log CFU/ml, respectively, while Ci 0.3 and 0.5% decreased by only 0.72 and 1.07 log CFU/ml, respectively. The population of E. coli O157:H7 was, however, decreased by 4.0 log CFU/ml with the combination of caffeine 0.4% and cinnamon 0.5 %.

Significance:   Our results indicate that caffeine and cinnamon are effective antimicrobials to control the survival and growth E. coli O157:H7. This could potentially be used as a better alternative to artificial preservatives in controlling foodborne pathogens in different liquid foods.