Antibacterial Activity of Cinnamaldehyde and Sporan against Escherichia coli O157:H7 and Salmonella

Abstract

The in vitro antimicrobial effect of cinnamaldehyde and Sporan in combination with acetic acid against Escherichia coli O157:H7 and Salmonella was investigated in Luria-Bertani broth (7 log cfu/mL) containing cinnamaldehyde or Sporan (800 and 1,000 ppm) alone or in combination with 200 ppm acetic acid, and incubated at 37C for up to 6 h. Surviving populations of test pathogens were determined by spiral plating on selective media. E. coli O157:H7 and Salmonella were undetectable after 1 h in the presence of 800 ppm cinnamaldehyde. A 1,000 ppm Sporan significantly reduced Salmonella and E. coli O157:H7 populations by 1.83 and 3.02 log cfu/mL within 2 and 4 h, respectively. Scanning and transmission electron microscopy of oil-treated bacterial cells revealed cell structural damage and leakage of cellular content. Cinnamaldehyde was highly effective against both E. coli O157:H7 and Salmonella whereas the effect of Sporan was dependent on its concentration, exposure time and pathogen. Practical Applications Consumers' preference for fewer chemicals in food has led to research on potential use of natural antimicrobials in food for controlling spoilage and pathogenic microorganisms. The antimicrobial effect of essential oils has been studied earlier. This is the first report on the antimicrobial activity of Sporan, and the combined effect of acetic acid. The results of the present study indicate that the antimicrobial activity of cinnamaldehyde and Sporan against enteric pathogens could be useful in food processing and preservation.