Evaluation of pH differential and HPLC methods expressed as cyanidin-3-glucoside equivalent for measuring the total anthocyanin contents of berries

摘要

The present study evaluated the accuracy of pH differential (PD) method and HPLC method expressed as cyanidin-3-glucoside equivalent (CGE) for measuring total anthocyanin (TA) contents of five berries. Major anthocyanins of blueberry, blackberry, black currant, raspberry, and cranberry were analyzed with quantitative HPLC (q-HPLC) method using individual anthocyanin standards and used as a standard reference of comparison. PD method and HPLC method showed similar trend, although absolute amounts of TA differed in blueberry and cranberry. However, data showed that the TA of black currant and raspberry expressed as CGE considerably deviated from those obtained by q-HPLC. This discrepancy was due to underestimating TA of these two berries which containdisaccharides as major glycones, when expressed as CGE. On the other hand, when expressed as their major anthocyanin equivalents, TA of these two berries showed better approximate values with those by q-HPLC method. In addition, this finding was confirmed by Bland–Altman analysis. Our findings demonstrated that the type of glycone in berries is a critical factor to cause discrepancy between TA as CGE and actual TA and should be considered for measuring TA contents.