Abstract:

Anthocyanin from flower petals of rose was assayed by single pH method at pH 1.0 and pH differential method at pH 1.0 and pH 4.5. Anthocyanin concentrate was obtained from dried flower petals of rose by extraction with 60% acidic ethanol solution, low-temperature vacuum concentration, and purification by sequential extraction with acetone and ether followed by AB-8 macroporous resin adsorption prior to determination. For reducing measurement error by the pH differential method, the anthocyanin concentrate should not be diluted to absorbance values at 518 nm below 0.2, and a big error was found at an absorbance value of 0.27. When determined using the single pH method, and the anthocyanin concentration should be controlled in the range from 3.5 to 13.8 mg/L. Single pH method was easily affected by the solvent concentration, and thus the determination by this method should be carried out using the same solvent.

Key words: rose, anthocyanin, single pH method, pH differential method