Antimicrobial activity of tea as affected by the degree of fermentation and manufacturing season by Chou CC；Chung KT；Lin LL
Bacillus subtilis, Escherichia coli, Proteus vulgaris,
Pseudomonas fluorescens, Salmonella sp. and Staphylococcus aureus
were used to test the antimicrobial activity of tea flush extract
and extracts of various tea products. Among the six test organisms,
P. fluorescens was the most sensitive to the extracts, while B.
subtilis was the least sensitive. In general, antimicrobial
activity decreased when the extents of tea fermentation increased.
The antimicrobial activities of tea flush extract andextracts of
tea products with different extents of fermentation varied with
test organisms. Tea flush and Green tea, the unfermented tea,
exerted the strongest antimicrobial activity followed by the
partially fermented tea products such as Longjing,Tieh-Kuan-Ying,
Paochung, and Oolong teas. On the other hand, Black tea, the
completely fermented tea, showed the least antimicrobial activity.
It was also noted that extracts of Oolong tea prepared in summer
exhibited the strongest antimicrobial activity, followed by those
prepared in spring, winter and fall.
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