What is "red yeast rice"

n. A variety of rice that is fermented with the mold (taxlink Monascus purpureus species noshow=1) until it turns red; used in whole and powdered form as a food coloring, food ingredient, and medicine in China and other Asian nations.

Red yeast rice , red rice koji (べにこうじ, lit. 'red koji') or akakoji (あかこぎ, also meaning 'red koji'), red fermented rice, red kojic rice, red koji rice, anka, or ang-kak, is a bright reddish purple fermented rice, which acquires its colour from being cultivated with the mold Monascus purpureus.

Red yeast rice is what is referred to as a "koji" in Japanese, meaning 'grain or bean overgrown with a mold culture', a food preparation tradition going back to ca. 300 BC. In both the scientific and popular literature in English that draws principally on Japanese, red yeast rice is most often referred to as "red rice koji". English works favoring Chinese sources may prefer the translation "red yeast rice".

Because of the low cost of chemical dyes, some producers of red yeast rice have adulterated their products with the dye Sudan Red G.