Reliability of analytical methods for determining anthocyanins in blood orange juices.

Quantitative analysis of anthocyanins was performed on a series of blood orange juices according to various spectrophotometric and HPLC methods, and the causes for different concentration resulting from the application of such procedures were investigated. Spectrophotometric methods utilizing aqueous ethanol as a solvent provided an anthocyanin content higher than that determined by HPLC. Discrepancies were ascribed to the use of impure standards and/or unsuitable calibration lines. The most consistent results with the HPLC findings were obtained by a method utilizing water as a solvent and cyanidin-3-glucoside as a standard. Actual concentration of anthocyanins in blood orange juice was remarkably lower than that currently determined by procedures used in the juice producing factories.