Improving the Phloroglucinolysis Protocol and Characterization of Sagrantino Wines Proanthocyanidins |
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Authors: | Panagiotis Arapitsas Daniele Perenzoni Graziano Guella Fulvio Mattivi |
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Affiliation: | 1.Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, 38098 San Michele all’Adige, Italy; (P.A.); (D.P.);2.Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo Trento, Italy;3.Department of Cellular, Computational and Integrative Biology, CIBIO, University of Trento, 38098 San Michele all’Adige, Italy |
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Abstract: | Proanthocyanidins are key metabolites that explain wine sensorial character (bitterness and astringency) and red wine color changes during aging. Therefore, a fast and accurate method to evaluate the degree of polymerization and the structural composition of the polymeric proanthocyanidins is a crucial analytical tool. Phloroglucinolysis is the most used method for this analysis but, unfortunately, the phloroglucinol adducts of the monomeric flavan-3-ols are not commercially available, making the results less accurate. The aim of this work was the isolation by semi-preparative high performance liquid chromatography (HPLC) of these non-commercial compounds and their use for the development of an accurate UHPLC-MS/MS protocol. The purity of each adduct was established via quantitative 1H-nuclear magnetic resonance (NMR) measurements with 3-trimethylsilyl-propionic-d4 acid sodium salt as the calibration standard. The developed method was applied to evaluate the proanthocyanidins profile of Sagrantino di Montefalco wines in comparison to other well-known tannic wines. Commercial, 6–8 years old Sagrantino wines were demonstrated to be very rich in epicatechin type B procyanidins, to have low galloylation %, and to have a high mean degree of polymerization of the proanthocyanidins with respect to the other analyzed wines. |
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Keywords: | Sangiovese Cabernet Sauvignon Tannat Merlot Nebbiolo polyphenols tannins condensed tannins phloroglucinol epicatechin quantitative NMR |
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