Cereal Chem 56:291 - 294.  |  VIEW ARTICLE
The pH-Sensitive Pigments in Pearl Millet.

R. D. Reichert. Copyright 1979 by the American Association of Cereal Chemists, Inc. 

Millet flour-water pastes changed color reversibly from gray to yellow-green at alkaline pH and partially reversibly from gray to creamy-white, in the presence of acid. The methanol extract of the flour contained the pH-sensitive pigments, which were identified by paper chromatography as glucosylvitexin, glucosylorientin, and vitexin in the ratio of 29:11:4. These compounds are responsible for the intense yellow-green discoloration of the flour in the presence of alkali and may be responsible for the natural gray color of the peripheral endosperm of the grain. The methanol-extracted millet flour also contained a substantial quantity of alkali-labile ferulic acid (ALFA). The concentrations of total C-glycosylflavones and ALFA were 124 and 158 mg/100 g, respectively, in whole grains, but they decreased markedly on dehulling.