Effect of Micelles and pH on Stability of Clitoria ternatea Color Extract

Abstract

Petal of Clitoria ternatea L. is an interesting source of natural colorants for pharmaceutical use. This work was to study the influences of pH and micelles on the color stability of Clitoria ternatea extract. The color changed from red to blue over pH 4 to 10. Degradation rate at various pH was in the order: pH 10 > 7 > 4 (% color remaining of <30, 50 and 80 at day 60, respectively). At pH 10 and 7 in the presence of micelles, color instability was in the order: cationic micelles > anionic micelles > nonionic micelles > buffer. At pH 4 in the presence of micelles, color instability followed the order: cationic micelles > nonionic micelles ~ buffer > anionic micelles (% color remaining of 47, 80, 80 and 85 at day 60, respectively). The color extract is stable at pH 4 but unstable in the presence of cationic micells at all pH.