Structural characterization of stalk lignin from banana plant

• Autor(a) principal: Oliveira, L.
• Data de Publicação: 2009
• Outros Autores: Evtuguin, D., Cordeiro, N., Silvestre, A.J.D.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/3358
• topic: Lignin; Musa acuminata Colla var. Cavendish; Rachis; Floral stalk; Banana plant; 13C NMR; 1H NMR; .; Faculdade de Ciências Exatas e da Engenharia

Dioxane lignins from two fractions of banana plant ‘Dwarf Cavendish’ stalk (floral stalk (DLFS) and rachis (DLR)) were structurally characterized by a set of spectroscopic (Ultravio let (UV), FTIR, solid- and liquid-state NMR) and chemical degradation (permanganate (PO) and nitrobenzene oxidation (NO)) techniques. Despite both lignins are of HGS-type, strong structural differences were observed between them. Thus, DLFS showed almost twice the abundance of H and G units and almost half of the abundance of S units when compared to DLR. DLR possessed significantly higher amount of -O-4 structures (0.32/C6 against 0.12/C6) and the molecular weight (5400 Da against 3750 Da) than those of DLFS. About 72% of the con densed structures in DLFS are of -5 and 5–5 types, whereas 4-O-5 -diaryl ether structures were the most abundant condensed structures in DLR. Most of H units in both lignins are terminal phenolic coumarates linked to lignin substructures by ester bonds. Both lignins are structurally associated with suberin-like components in cell wall tissues. Structural fea tures of stalk lignin were discussed in terms of possible restrictions for the kraft pulping of integral stem material.