Antibacterial effect of crude water-soluble arrowroot (Puerariae radix) tea extracts on food-borne pathogens in liquid medium.
OBJECTIVE
To evaluate the effect of crude water-soluble arrowroot tea extracts on microbial growth of food-borne pathogens in liquid medium and to confirm the damage to bacterial cells using Transmission Electronic Microscopy (TEM).


RESULTS
Inhibition of growth of Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Listeria monocytogenes and Staphylococcus aureus was investigated using Brain Heart Infusion (BHI) broth containing 0 (control), 0.63, 1.25, 2.5 and 5.0% (w/v) arrowroot tea. Bacterial cell counts were performed on specific selective agar on days 0, 1, 3 and 5. BHI containing 5.0% arrowroot tea extract showed a 6-7 log suppression of growth for all test strains on days 3 and 5, compared with the control. Even 0.63% arrowroot tea effectively inhibited microbial growth of all test strains on day 5. TEM images of the samples treated with 5.0% arrowroot tea revealed the rupture of cell walls and nonhomogeneous disposition of cytoplasmic materials within treated bacteria.


CONCLUSIONS
Crude water-soluble arrowroot tea extract strongly inhibited microbial growth of all test pathogens in liquid medium.


CONCLUSIONS
Water-soluble arrowroot tea extract has the potential to be used directly on foods or as a spray on the surfaces of food handling and processing facilities in order to prevent microbial growth of both Gram-negative and Gram-positive bacteria.
Kim
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Department of Animal Sciences and Industry, Food Microbiology Laboratory, Kansas State University, Manhattan, KS 47907-2009, USA. kim98@purdue.edu
Fung
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D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001628:Beverages; D002473:Cell Wall / Q000187:drug effects; D015169:Colony Count, Microbial; D003470:Culture Media; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000648:ultrastructure; D005516:Food Microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010936:Plant Extracts / Q000494:pharmacology*; D029908:Pueraria / Q000737:chemistry*; D012995:Solubility
D000900:Anti-Bacterial Agents; D003470:Culture Media; D010936:Plant Extracts