Abstract
Stability of indigo carmine in 60% sugar dissolved in distilled water, citrate-phosphate buffers of pH 6.40 and 5.25, and phosphate buffer of pH 6.20, respectively, was compared between beet and cane sugar. Under these conditions, the color stability during storage in the dark at 37°C, or on exposure to xenon lamp, was generally greater in beet sugar solution than in cane sugar. An unusual fading of the color was observed in the solution of one commercial beet sugar sample. On exposure to fluorescence lamp, the color stability in this beet sugar solution increased with time after preparation of the solution. As the sugar solution reduced methylene blue, the color fading mentioned above may be due to structural change caused by reduction.
