29F-9 |
Antimicrobial effect of Thai spices against Listeria monocytogenes and Salmonella Typhimurium DT104 |
C. THONGSON1, P. M. Davidson2, W. Mahakarnchanakul3, and P. Vibulsresth3. (1) Department of Food Science and Technology, University of Tennessee, 2509 River Drive, Knoxville, TN 37996-4539, (2) Dept. of Food Science & Technology, Univ. of Tennessee, 2509 River Dr., 201 Mcleod Food Tech Bldg., Knoxville, TN 37966-4539, (3) Department of Food Science and Technology, Kasetsart University, 50 Pahonyothin, Bangkhen, Jatujak, Bangkok, 10900, Thailand One method for inhibiting pathogenic bacteria to improve food safety is use of food antimicrobials. However, regulatory-approved antimicrobials have limitations which have led to research on novel natural compounds. Spices and their essential oils have demonstrated varying degrees of antimicrobial activity and may contribute to improving food safety by inhibiting foodborne pathogens. The objective of this study was to investigate the antimicrobial efficacy of the Thai spices, ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata) and turmeric (Curcuma longa), against Listeria monocytogenes and Salmonella Typhimurium DT 104. L. monocytogenes 101, 108, 310, Scott A and V7 and Salmonella Typhimurium DT104 2380, 2486, 2576, and 2582 were used in the study. Ginger, fingerroot and turmeric were obtained fresh from a market in Bangkok or as commercial essential oils (TCFF, Ayutthaya, Thailand). Fresh spices were extracted with water or 50% ethanol. Antimicrobial activity was determined in an agar dilution assay or by enumeration over time. Water extracts of the 3 spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5% (v/v) inhibited most L. monocytogenes strains for 24 hr in the agar dilution assay. Commercial essential oil (EO) of ginger or turmeric inhibited all L. monocytogenes at 0.4% or 1.0%, respectively. Fingerroot EO inhibited all strains at 0.3%. A 5% fingerroot ethanol extract reduced Listeria viable counts slightly while 10% inactivated the microorganism in 9 hr. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 9 hours. Neither extracts nor commercial EO had any effect on S. Typhimurium DT 104 except for fingerroot EO which inhibited all strains at 0.5%. Among the Thai spices tested, fingerroot had the greatest antimicrobial activity. These spices, especially fingerroot EO, have potential for inhibiting pathogens in food systems.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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