Orcein (Orcein, archil, orchil, lacmus, litmus, orcein, orsin, litmus, E182) - tsaus xim av muaju. Lawv hloov xim rau xim liab nyob rau hauv ib puag ncig acidic thiab xiav nyob rau hauv ib qho alkaline. Tshuaj formula C28H24N2O7.
Cov yeeb tshuaj no tau cais tawm ntawm cov npe "Cov khoom noj ntxiv rau kev tsim khoom noj" rau Txoj Cai Tswj Xyuas Kev Ua Kom Zoo thiab Kev Ua Si (SanPiN 2.3.2.2364-08) hauv 2008.