Quantification of polyphenols in freeze-dried table grape powder

Bioactive polyphenolic compounds such as phenolic acids, cinnamic acids, stilbenes, flavonoids, flavans, flavonols and anthocyanins are associated with the prevention of degenerative diseases such as cardiovascular disease and certain types of cancers. These polyphenols – specifically catechin, epicatechin, peonidin, cyanidin, malvidin, quercetin, kaempferol, isorhamnetin, and resveratrol – are found in various plants such as grapes. In this study, polyphenols in freeze-dried table grape powder prepared from red, green and black grapes (California Table Grape Commission) were extracted using various methods. Polyphenols in the extracts were characterized and quantified using ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The chemically standardized grape powder is suitable for studies of the health benefits of grapes in animal and clinical studies.