High performance liquid chromatography (HPLC) has been used to examine chemical differences between tea beverages that are freshly brewed and those which come in a bottle.
Dr Shiming Li, a natural product chemist at New Jersey biotechnology firm WellGen, led a team using HPLC to analyse polyphenol levels in fresh tea and in bottled health drinks.
In some cases, the bottled beverages had levels of the antioxidants equivalent to around five per cent of the quantity seen in a single freshly brewed cup of either green or black tea.
Dr Li says: "Consumers understand very well the concept of health benefits from drinking tea or consuming other tea products."
However, the research indicates a "huge gap" between these perceptions and the true health benefits of pre-prepared beverages.
The data was presented to the American Chemical Society on August 22nd at its autumn 2010 national meeting, which is focusing on the chemistry of disease prevention.
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