Posted by:
captaincaveman
(
)
Date: March 24, 2011 01:24PM
The tannic acid used to tan leathers is different than the tannins found in some caffeinated beverages.
"While 'tannic acid' is a specific type of 'tannin' (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably. The long standing misuse of the terms, and its inclusion in scholarly articles have compounded the confusion. This is particularly widespread in relation to green tea and black tea. Although tea contains tannin and various types of polyphenols, "contrary to widespread belief, tea does not contain tannic acid." -- wikipedia
"Plant polyphenols are generically known as ‘‘tannins’’ (14).
These are perceived in general as toxic compounds (37), perhaps because of their ability to precipitate proteins. This property, called ‘‘astringency’’ in a chemical sense, was taken advantage of clinically in former times, when tannic acid
ointment was used to treat superficial burns. It is very important to note, however, that tea tannins are chemically different
from other plant tannins and in no way conform to descriptions
of tannic acid (37, 47). "
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC162950/pdf/392375.pdf