Wine metabolomics constitutes a powerful discipline towards wine authenticity assessment through the simultaneous exploration of multiple classes of compounds in the wine matrix. Over the last decades, wines from autochthonous Greek grape varieties have become increasingly popular among wine connoisseurs, attracting great interest for their authentication and chemical characterization. In this work, 46 red wine samples from Agiorgitiko and Xinomavro grape varieties were collected from wineries in two important winemaking regions of Greece during two consecutive vintages and analyzed using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS). A targeted metabolomics methodology was developed, including the determination and quantification of 28 phenolic compounds from different classes (hydroxycinnamic acids, hydroxybenzoic acids, stilbenes and flavonoids). Moreover, 86 compounds were detected and tentatively identified via a robust suspect screening workflow using an in-house database of 420 wine related compounds. Supervised chemometric techniques were employed to build an accurate and robust model to discriminate between two varieties.
Polyphenols are a diverse group of compounds possessing various health-promoting properties that are of utmost importance for many wine sensory attributes. Apart from genetic and environmental parameters, the implementation of specific oenological practices as well as the subsequent storage conditions deeply affect the content and nature of the polyphenols present in wine. However, polyphenols are effectively employed in authenticity studies. Provision of authentic wines to the market has always been a prerequisite meaning that the declarations on the wine label should mirror the composition and provenance of this intriguing product. Nonetheless, multiple cases of intentional or unintentional wine mislabeling have been recorded alarming wine consumers who demand for strict controls safeguarding wine authenticity. The emergence of novel platforms employing instrumentation of exceptional selectivity and sensitivity along with the use of advanced chemometrics such as NMR (nuclear magnetic resonance)- and MS (mass spectrometry)-based metabolomics is considered as a powerful asset towards wine authentication.
This study evaluated the antioxidant capacity, total phenol content, and sensory profile of selected Greek wines made from Vitis vinifera L. c.v. Moschofilero in two consecutive vintages, treated with powdered Hippophae rhamnoides L. leaves (HRL). Radical Scavenging activity, reducing power, total phenol content (TPC), and color intensity increased in a linear manner in relation to HRL treatments. Indicatively the addition of 0.8 g/L of HRL increased the radical scavenging activity as determined via the inhibition of the 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical from 28.4 to 55.8% in comparison to the initial values. Equally the reducing power as determined by the ferric reducing antioxidant power (FRAP) assay increased from 35.3 to 62.1%, and total phenol content values increased from 11% to 23.7% and the color intensity increased from 39.9 to 50.7%. The main oenological attributes examined, remained unchanged after the HRL addition. The addition of up to 0.4 g/L of HRL did not have a major impact on the organoleptic characteristics of the wines tasted whereas concentrations higher than 0.8 g/L were not considered beneficial. Results denote that the addition of H. rhamnoides leaves to white wines contributes positively to the overall antioxidant capacity and could be used if authorized as an antioxidant agent in wines vinified in the absence of or in synergy with sulphur dioxide.
This study evaluated the influence of the addition of increasing quantities of Hippophae rhamnoides L. leaves (HRL) on the radical scavenging activity, main oenological parameters and organoleptic characteristics of three white wines made from moschofilero and one white wine made from riesling grapes respectively. Radical Scavenging activity, reducing power, total phenol content (TPC) and color intensity increased in a linear manner in relation to HRL treatments. Indicatively the addition of 0.8 g/L of HRL increased the radical scavenging activity as determined via the inhibition of the DPPH radical from 23.2 to 58.4% in comparison to the initial values. Equally the reducing power as determined by the FRAP assay increased from 34.5 to 82.3%, TPC increased from 12.3 to 26.8% and the color intensity increased from 39-50% . The main oenological attributes examined, remained unchanged after the HRL addition. The addition of up to 0.4 g/L of HRL did not have a major impact on the organoleptic characteristics of the wines tasted whereas concentrations higher than 0.8 g/L were not considered beneficial. Results denote that the addition of Hippophae rhamnoides L. leaves to white wines contributes positively to the overall antioxidant capacity and could be used as an antioxidant agent in wines vinified in the absence of sulphur dioxide.
Στο ανταγωνιστικό πλαίσιο της διεθνούς οινικής αγοράς, η αναζήτηση καινοτόμων οινοποιητικών μεθόδων και επιβεβαιωμένα αυθεντικών οίνων αποτελούν ένα προαπαιτούμενο. Η παρούσα εργασία έχει στόχο αρχικά να διερευνήσει διαφορετικές οινοποιητικές τεχνικές χωρίς προσθήκη θειωδών. Επίσης έχει ως στόχο την ανάπτυξη μεθόδων για την μελέτη του μεταβολομικού προφίλ τόσο οίνων χωρίς θειώδη όσο και συμβατικών με χρήση υγρής χρωματογραφίας υπερυψηλής απόδοσης συζευγμένης με φασματομετρία μάζας υψηλής διακριτικής ικανότητας (UHPLC/Q-ToF-MS/MS). Στο πρώτο μέρος του πειραματικής διαδικασίας έγιναν οινοποιήσεις με/χωρίς θειώδη σε διαφορετικές ποικιλίες αμπέλου. Παρουσιάζονται οι διαφορές που παρατηρήθηκαν, όσον αφορά στις βασικές οινολογικές αναλύσεις, επιλεγμένους μεταβολίτες, περιεχόμενο σε ολικές φαινόλες καθώς και στην αντιοξειδωτική ικανότητα. Παρουσιάζεται επίσης, η επίδραση της προσθήκης αλεσμένων φύλλων ιπποφαούς σε οίνους χωρίς θειώδη τόσο στο οργανοληπτικό προφίλ όσο και σε επιλεγμένους δείκτες.Οι σύγχρονες αναλυτικές διατάξεις παρέχουν μια νέα προοπτική έναντι του παραδοσιακού οργανοληπτικού ελέγχου στην αξιολόγηση της αυθεντικότητας των οίνων. Πέραν των οινοποιήσεων χωρίς θειώδη, σε αυτή την μελέτη ελέγχθηκαν 97 δείγματα λευκών και 46 δείγματα ερυθρών οίνων με χρήση UHPLC/Q-ToF-MS/MS. Αναπτύχθηκαν και επικυρώθηκαν μέθοδοι τόσο για «στοχευμένη» σάρωση όσο και για «ύποπτη» σάρωση των δειγμάτων. Έγινε μονοπαραγοντική ανάλυση για την αναγνώριση ομοιοτήτων/διαφορών αναμεσά στους οίνους από διαφορετικές ποικιλίες αμπέλου για κάθε μεταβλητή. Εφαρμόστηκαν επιβλεπόμενες πολυπαραγοντικές στατιστικές μέθοδοι με χρήση αλγόριθμού μηχανικής μάθησης τυχαίων δασών για τους λευκούς οίνους καθώς και ορθογώνια διακρίνουσα ανάλυση μερικών ελαχίστων τετραγώνων για τους ερυθρούς οίνους. Κατασκευάστηκαν αξιόπιστα προγνωστικά μοντέλα με ιδιαίτερα ικανοποιητικά αποτελέσματα αναφορικά με την ευαισθησία και την επιλεκτικότητα τους για όλες τις κλάσεις. Αναγνωριστήκαν οι κύριοι βιοδείκτες που επέδρασαν σημαντικά στην διάκριση των ποικιλιών.
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