29F-10 |
Antimicrobial effect of water extract of Arrowroot (Maranta arundinacea) tea on foodborne pathogens in liquid medium |
S. KIM, Animal Sciences and Industry, Kansas State University, Call Hall 202, Manhattan, KS 66506 and D. Y. C. Fung. Various teas have been studied for their antimicrobial effects against many bacteria. In a preliminary study we found that water extract of Arrowroot tea at 10% (w/v) greatly inhibited the microbial growth of gram-positive and gram-negative pathogens tested. This study was to ascertain the minimum inhibition concentration of Arrowroot tea at concentrations of 0, 0.63, 1.25, 2.5, and 5.0% (w/v) in Brain Heart Infusion (BHI) medium. The cocktail of four pathogenic bacteria (Escherichia coli O157:H7 ATCC 35150, Salmonella enteritidis USDA-FSCS 15060, Listeria monocytogenes ATCC 19115, and Staphylococcus aureus ATCC 25178) was inoculated into Arrowroot tea solutions at 3 log cfu/ml. After incubation at 35°C for 0, 1, 3, and 5 d, each sample was serially ten-fold diluted and spread-plated on Plate Count Agar for total cells and pathogen-specific agar for each pathogen, in duplicate. After incubation at 35°C for 24-36 h, viable cell counts were obtained. All pathogens on PCA grew from 4 log cfu/ml to 8-9 log cfu/ml in all concentrations at 1 d. They reduced to 4-6 log cfu/ml at 3 d and 1 log cfu/ml at 5 d. E. coli O157:H7 on MSA, S. enteritidis on XLD, L. monocytogenes on MOX, and S. aureus on BP reduced to ca. 3-4 log cfu/ml at 3 d and 1 log cfu/ml at 5 d in 0.63%, 1.25%, and 2.5%, while they reduced to 1 log cfu/ml at 3 d in 5%. The results indicated that 0.63% of Arrowroot tea was effective in inhibiting all pathogens to the minimum detection limit of 1 log cfu/ml at 5 d.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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