COMPOSITION IN POLYPHENOLS AND STABILITY OF THE AQUEOUS GRAPE SEED EXTRACT FROM THE ROMANIAN VARIETY “MERLOT RECAS”

Abstract

ABSTRACT The aim of this study was to characterize flavan-3-ol and oligomeric proanthocyanidin composition of the aqueous grape seed extract (GSE) from the Romanian wine grape cultivar “Merlot Recas.” For the isolation and identification of these antioxidant compounds, liquid chromatography-electrospray ionization-mass spectrometry was used. Grape seeds from the Romanian cultivar “Merlot Recas” appear a promising source of polyphenolic compounds. The aqueous extract is rich in catechin, epicatechin and procyanidins (dimers and trimers) known to be chemopreventive nutraceuticals. The evolution of flavan-3-ols and procyanidins in GSE was investigated, showing that the watery extract is very unstable, its phenolic composition not being preserved during 6 months at 4C. This work is a contribution to the know-how over fingerprinting and valorization of cheap sources for added value products as grape pomace and grape seeds out of it. PRACTICAL APPLICATIONS The most abundant phenolics isolated from grape seeds, collected from the grape pomace, are catechins (catechin and epicatechin) and their polymers, the procyanidins. The obtained data can serve as a helpful tool in the analysis of dietary supplements made from grape seeds and commercialized as grape seed extract, especially those in liquid forms. Composition and stability of flavan-3-ols and procyanidins, in aqueous extracts, has an important role in performing biochemical tests in vitro on cell culture. Our results can be used also for dealing with the waste disposal during the process of wine making, the waste serving as a natural source of the chemopreventive flavan-3-ols and procyanidins.