Antimicrobial activity of cloves and cinnamon extracts against food borne pathogens and spoilage bacteria, and inactivation of Listeria monocytogenes in ground chicken meat with their essential oils

Abstract

Ethanol, aqueous extracts, and essential oils of Cloves (Syzygium aromaticum), and Cinnamon (Cinnamomum cassia) were analyzed for determination of antibacterial activity against 21 food borne pathogens: Listeria monocytogenes (5 strains), Staphylococcus aureus (4 strains), Escherichia coli O157: H7 (6 strains), Salmonella Enteritidis (4 strains), Vibrio parahaemolyticus and Bacillus cereus and 5 food spoilage bacteria: Pseudomonas aeroginosa. P. putida, Alcaligenes faecalis, and Aeromonas hydrophila (2 strains). Screening of cloves and cinnamon extracts showed antibacterial activity against the test organisms. The MIC values for ethanol, aqueous extracts, and essential oil from cloves ranged from 0.5 to 5.5 mg/ml, 0.8 to 5.5 mg/ml, and 1.25 to 5%, respectively. The MIC values for ethanol, aqueous extracts, and essential oil from cinnamon ranged from 1.0 to 3.5mg/ml, 2.5 mg/ml, and 1.25 to 5.0%, respectively. The effect of temperature and pH on the antibacterial activity of essential oils of cloves and cinnamon against cocktails of different strains of L. monocytogenes, E. coli O157: H7 and Salmonella Enteritidis were determined. The essential oils (EO) of cloves and cinnamon showed antibacterial activity after treatment at 100 deg C for 30 min suggesting that the high temperature does not affect the activity of these EO. The highest antibacterial activity was found at pH 5.0 for EO of cloves and cinnamon against most of the bacterial mixtures except for L. monocytogenes, where the highest activity was found at pH 7.0. The EO of cloves (10 %) and cinnamon (5 %) were applied in ground chicken meat inoculated with a cocktail of 5 strains of Listeria monocytogenes. The result showed that EO of cloves reduced all Listeria monocytogenes cells to an undetectable level in ground chicken meat within 1 day of exposure. However, the EO of cinnamon reduced Listeria monocytogenes in ground chicken meat by 2.0 log CFU/g within 1 day with only slight reductions or no further decline in cell population throughout the 15 days incubation period. Therefore, EO of clove could be useful to control L. monocytogenes in ground chicken meat.