[[Berkas:Bottle of tannic acid.jpg|thumb|right|250px|Sebotol asam tannin.]]
'''Tannin''' areadalah [[astringent]], bitter plant [[polyphenol]]s that either bind and [[precipitate]] oratau shrinkmengecilkan [[protein]]s. The astringency from thedari tannin is what menyebabkan perasaan kering pada mulut dengan konsumsi wina merah, strongteh teastrong, oratau anbuah unripened fruit.<ref>McGee, Harold. On Food and Cooking. Simon & Schuster. New York, NY 2004 pg714</ref>. Istilah tannin merujuk pada penggunaan tannin dalam [[tanning]] animal [[hides]] into [[leather]]; namun, istilah ini secara luas dirujukan untuk any large [[polyphenolic]] compound containing sufficient [[hydroxyl]]s and other suitable groups (such as [[carboxyl]]s) untuk membentuk strong complexes dengan protein and other [[macromolecule]]s. Tannin memiliki [[berat molekul]] dari 500 hingga 3.000.<ref name="Bate-Smith">Bate-Smith and Swain, 1962, Flavonoid compounds. In : Comparative biochemistry. Florkin M. Mason H.S. Eds. Vol III. 75-809. Academic Press, New-York.</ref> Tannins are incompatible with alkalies, gelatin, heavy metals, besi, lime water, metallic salts, strong oxidizing agents dan zinc sulfate.
