Tea Anti-Microbial Properties
DRice at drice.ehs.colostate.edu
Thu Oct 19 12:38:09 EST 1995
In article <3085719D.7065 at bu.edu> Allen Wang <alwang at bu.edu> writes:
>From: Allen Wang <alwang at bu.edu>
>Subject: Tea Anti-Microbial Properties
>Date: Wed, 18 Oct 1995 14:29:01 -0700
>Does anyone know if tea has anti-microbial properties?
>If so, which ones?
Which type of tea?
Herbal teas tend to have very high background counts of yeast, mold, and yes,
coliforms. This is due to the exotic origins of the diverse ingredients.
Most herbal teas, however, have acidic ingrediets to lower the pH to an acid
food level (<4.5). The pH is the most important hurdle to protect herbal
teas. Acidic ingredients include: hybiscus, rose hips, lemon grass, citric
acid from orange, or lemon peel. Some herbal teas actually have added acids
such as citric and phosphoric. Some of the other ingredients have volitile
oils that are classically anti-microbial: cinnamon and clove oil.
Black teas are naturally much lower in resident populations due to their
production process. All black teas go through a fermentation and aging
process that first decreases the pH and later reduces the water activity.
Black teas also have important "anti's" such as tannic acid that results from
the fermentation process.
The most import anti-microbial for tea is of course boiling water.
Considering some of the resident organisms that I have found in all types of
tea, I would not dring unheated tea.
I hope this has been some help!!!
Doug Rice: Laboratory Director; Environmental Quality Laboratory
Microbiology of water, food, soil, and air.
Colorado State University: Ft Collins, Colorado.
e-mail: drice at vines.colostate.edu voice: (970) 491-6503
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