Spectrophotometric determination of the tannin contents of various Turkish black tea, beer and wine samples.

This study reports tannin contents of various tea (19), beer (6) and wine (6) samples, produced or sold in Turkey under different brand names. Determinations were carried out by employing a previously reported UV-vis spectrophotometric method. The standard addition procedure was also compared to the direct determination procedure and found to be more reliable. The tannin contents of hot water extracts of tea, tea bag and herbal tea samples ranged between 6.20-8.33, 8.03-6.59 and 2.76-6.54 percent (w/w) respectively. Tannin contents of beer and wine samples determined without extraction were found ranging between 66.36-77.26 and 67.18-107.62 micrograms/mL respectively. Iron contents of analysed wine samples were also found ranging between 0.36 and 10.33 ppm by AAS and no relation is found between tannin and iron contents.