Quantification of anthocyanidins in the grapes and grape juice products with acid assisted hydrolysis using LC/MS

A simple and precise acid-assisted hydrolysis method was established for the quantification of anthocyanidins in 15 grape juice samples, four grape berries and four grape skins using LC/MS. Under optimized conditions, five major anthocyanidins including delphinidin, cyanidin, petunidin, peonidin and malvidin in the hydrolyzed grape extracts were successfully separated within 25. min and quantified individually. The results revealed that the total concentration of anthocyanidins was not symmetrically distributed in the different grape juice products. While quantitative distribution of anthocyanidins in grape berries and skins are quite similar, anthocyanidin concentration in grape skins was found to be four to eight times higher than their corresponding berries. The precision of this method was validated by recovery percentages of five anthocyanidins, ranging from 98.59% to 103.20% with the relative standard deviation (RSD) less than 5.03%. This quantitative method provides a rapid and accurate tool to quantitatively study individual anthocyanidins in grapes or grape juice samples for quality control and to facilitate the evaluation and comparison of new commercial grapes or grape juices products in the market.