STUDY ON ISOLATION AND PURIFICATION OF ANTHOCYANINS AND ITS APPLICATION AS pH INDICATOR

Extraction and purification of Anthocyanin pigments from Black Raspberries (Rubus occidentalis) was successfully carried out. Homogeneous and fine powder was obtained from the liquid nitrogen blending process. After extraction and purification of the plant material, a colored solution was obtained. Depending on the nature of the predominant anthocyanin and its concentration, the coloration of the solution is pink/red or purple. The solution obtained after extraction was dark brownish red coloured. Two different methods were used for extraction viz. extraction with acetone/chloroform partitioning and extraction with methanol. In the acetone/chloroform procedure, the upper phase shows colouration due to extraction of pigment in acetone while chloroform containing layer is only slightly coloured. The extraction was followed by partial purification procedures using Column chromatography and TLC. The column chromatography process was optimized for methanol extracts. The fractions collected from column analysis were subjected to thin layer chromatography. TLC analysis revealed the presence of Anthocyanins in all fractions in varying concentrations but only fraction-4 was shown to have the Rf value close to that of pure Anthocyanins. Anthocyanin as natural pH indicator was studied.