Identification of flavonol glycosides in winemaking by-products by HPLC with different detectors and hyphenated with mass spectrometry

The recovery of high added-value products from waste plant material has been an important issue with economic relevance for the pharmaceutical and food industries. The recovery of antioxidants from wine industry by-products is of great importance in the nutraceutical field. The aim of this study was to identify the main flavonol glycosides, present in winemaking by-products from two white grape varieties: ‘Arinto’ and ‘Moscatel’ using liquid chromatography with diode array and electrochemical detection. Liquid chromatography with electrospray and atmospheric pressure chemical ionization, in negative and positive modes, were also used to characterize the structures of the compounds detected by means of MS²and MS ³. In the by-products analysed quercetin-3-glucoside and quercetin-3-glucuronide were identified as well as kaempferol-3-glucoside. By-products from ‘Arinto’ variety showed higher levels of quercetin glycosides and kaempferol-3-glucoside than the by-products of ‘Moscatel variety’.