Abstract
Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was observed for all the analyzed compounds. Using MS/MS hydroxybenzoic acid and hydroxycinnamic acids showed a loss of CO2 and production of a [M-H-44]- fragment and as expected, the UV spectra of these two compounds were affected by their chemical structures. For flavonol and flavonol glycosides, the spectra of their glycosides and aglycones produced deprotonated [M-H]- and [A-H]- species, respectively, and their UV spectra each presented two major absorption peaks. The UV spectra and MS/MS data of flavan-3-ols and stilbenes were also investigated. Using the optimized LC/MS/MS analytical conditions, the phenolic extracts from six representative wine samples were analyzed and 31 phenolic compounds were detected, 26 of which were identified by searching the LC/UV and MS/MS libraries. Finally, the presence of phenolic compounds was confirmed in different wine samples using the LC/UV and LC/MS/MS libraries.
Highlights
Phenolics, important secondary metabolites in the grape berry, play a critical role in determining the organoleptic characteristics of berries and wines
The phenolic compounds in red wines mainly comprise \simple phenolic acids and complicated polyphenols which are mainly derived from grape skins and seeds during the vinification process [12], or from yeast metabolites and aging in oak barrels
To determine the most effective ionization mode for the phenolic standards (250 mg L-1), atmospheric pressure chemical ionization (APCI) or a electrospray ionization (ESI) source in positive- or negative-ion modes were investigated The results indicated that the ESI source at negative-ion mode with a MS/MS activation energy of 1.0V was best for the analysis of low-molecular phenolic compounds, which coincided with the previous reports [23, 25]
Summary
Important secondary metabolites in the grape berry, play a critical role in determining the organoleptic characteristics of berries and wines. In particular they contribute to wine characteristics such as color, flavor, astringency and bitterness [1,2,3]. Phenolic compounds are associated with cardiovascular benefits, such as reducing platelet aggregation and modulating eicosanoid synthesis. The study of phenolic compounds, such as the amounts and species found in red wine, where they are more abundant than in white wine, has attracted considerable attention among the food safety community. The phenolic compounds in red wines mainly comprise \simple phenolic acids (e.g. hydroxybenzoic acid and hydroxycinnamic acid) and complicated polyphenols (e.g. flavonols, anthocyanin and tannins) which are mainly derived from grape skins and seeds during the vinification process [12], or from yeast metabolites and aging in oak barrels
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
