Hordeumin, a type of novel purple anthocyanin-tannin pigment, was produced from barley bran-fermented broth. The mutagenicity or antimutagenicity of hordeumin was investigated according to the Ames method, an indication of the safety of food, using Salmonella typhimurium TA98. Hordeumin is a precipitate formed by storing fermented filtrate containing hordeumin precursors in an oxidative environment. The hordeumin formed by the ethanol fermentation of uncooked barley bran had properties partially different from those of conventional anthocyanins and showed high molecular tannin-like properties. Hordeumin formation was inhibited by addition of radical scavengers or antioxidants to the barley bran-fermented filtrate. The pigment retention rate of hordeumin was higher than that of two standard anthocyanidins, cyanidin and delphinidin, when hordeumin and anthocyanidins were dissolved in Walpole buffer (pH 1.0) and stored.