The effect of the addition of various surfactants on the colour stability of various anthocyanin source extracts

Clitoria ternatea (CT), Ipomoea tricolor (IT), Ipomoea batatas (IB), Hibiscus rosa-sinensis L. (HR), and Ruellia tuberosa (RT) were used as the natural anthocyanin sources. The anthocyanin extract solutions were extracted and diluted under buffer pH 4, 5, 6, and 7 along with the addition of (Sodium dodecyl sulphate) SDS, (cetyltrimethylammonium bromide) CTAB, and Triton X-100. The changes were recorded using UV-Vis Spectrophotometer under visible region (400-700 nm) over various storage time. In polyacylated CT and IT samples, SDS was the best stabilizing agent at pH 4 and 5 while CTAB was ineffective on maintaining the color stability at all pH condition. In monoacylated IB sample, SDS worked best at pH 7 while CTAB capability was low on the color stability at pH 4. In unacylated HR and RT samples, SDS worked best at HR extract solution at pH 4 and RT extract solution pH 4 and 5. At both pH 6 and pH 7, all surfactants did not affect the color stability. The presence of Triton X-100 did not make any significant change on color stability of anthocyanin extract solutions. To conclude, SDS was the best surfactants as the stability was high. On the other hand, CTAB and Triton X-100 was not appropriate on retaining the color intensity.