Structural Characterization of Lignin from Grape Stalks (Vitis vinifera L.)
authors Prozil, SO; Evtuguin, DV; Silva, AMS; Lopes, LPC
nationality International
journal JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
author keywords grape stalks; dioxane lignin; nitrobenzene oxidation; permanganate oxidation; H-1 NMR; C-13 NMR; HSQC; FTIR; UV-vis
keywords CHEMICAL-COMPOSITION; MACROMOLECULAR COMPONENTS; HIBISCUS-CANNABINUS; WOOD; FEATURES; WASTE; PORTUGAL; HARDWOOD; POMACE; WINERY
abstract The chemical structure of lignin from grape stalks, an abundant waste of winemaking, has been studied. The dioxane lignin was isolated from extractive- and protein-free grape stalks (Vitis vinifera L.) by modified acidolytic procedure and submitted to a structural analysis by wet chemistry (nitrobenzene and permanganate oxidation (PO)) and spectroscopic techniques. The results obtained suggest that grape stalk lignin is an HGS type with molar proportions of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units of 3:71:26. Structural analysis by H-1 and C-13 NMR spectroscopy and PO indicates the predominance of beta-O-4' structures (39% mol) in grape stalk lignin together with moderate amounts of beta-5', beta-beta, beta-1', 5-5', and 4-O-5' structures. NMR studies also revealed that grape lignin should be structurally associated with tannins. The condensation degree of grape stalks lignin is higher than that of conventional wood lignins and lignins from other agricultural residues.
publisher AMER CHEMICAL SOC
issn 0021-8561
year published 2014
volume 62
issue 24
beginning page 5420
ending page 5428
digital object identifier (doi) 10.1021/jf502267s
web of science category Agriculture, Multidisciplinary; Chemistry, Applied; Food Science & Technology
subject category Agriculture; Chemistry; Food Science & Technology
unique article identifier WOS:000337720100004
link 24892733
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