29F-25 |
Preparation and evaluation of selected natural plant extracts as antimicrobial agents against Listeria monocytogens, Salmonella typhimurium and E. coli 0157:H7 |
R. CAI1, N. S. HETTIARACHCHY1, D. C. Bryant1, M. G. Johnson1, M. E. Janes2, and M. F. Slavik3. (1) Dept. of Food Science, Univ. of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704-5690, (2) Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200, (3) Dept. of Poultry Science, Univ. of Arkansas, Center of Excellence for Poultry Science, 1260 W. Maple, POSC 0-114, Fayetteville, AR 72701 Listeria m., Salmonella t., and E. coli 0157:H7 are the major food-borne pathogens that are a great concern to consumers and cost annual significant losses to food industry. Practical and efficient intervention techniques are needed for foods during processing to ensure the microbial safety of the products. There has been interest in identifying antimicrobial components from natural plant extracts because of safety and availability. Many compounds such as phenolics showing antimicrobial activities have been isolated from plants. Our objective was to prepare extracts from selected plants and to evaluate their effectiveness as antimicrobial agents against the three food-borne pathogens. Extracts were prepared from black tea, fenugreek, ginger, coriander, rice bran from local market, by extraction with 70% ethanol, hot water and cold water. A commercial grape seed water extract was also included. These extracts were evaluated for antimicrobial activities against Listeria m., Salmonella t. and E. coli 0157:H7 using Procedure I, inoculated and incubated in brain heart infusion (BHI) for 24 h, and Procedure II, inoculated and incubated in phosphate buffer saline (PBS) for 1 h before plating for bacteria counts, which tested the inhibiting and killing effect of the extracts. Black tea hot water extract and the grape seed extract were the most promising antimicrobial agents from the plant extracts studied. Tested in BHI for 24 h, black tea hot water extract (20 mg/mL) was very potent in inhibiting the growth of Listeria m. with a log reduction of 5.86, whereas grape seed extract (40 mg/mL) was potent in inhibiting Salmonella t. and E. coli 0157:H7 with log reductions of 6.55 and 6.68, respectively. Our results suggest that black tea and grape seed extract are effective antimicrobial agents that could be used in food application to inhibit the growth of the three bacteria to improve food safety.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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