Characterization of Residual Lignin Obtained by the Enzymatic Hydrolysis of Oil Palm Empty Fruit Bunch Pulps

• Published in: Bioresources Vol. 12; no. 1; pp. 183 - 194
• Main Authors: H'ng, Yin Ying, Nakagawa-Izumi, Akiko, Leh, Cheu Peng, Das, Atanu Kumar, Ohi, Hiroshi
• Format: Journal Article
• Language: English
• Published: North Carolina State University 01.01.2017
• Subjects: Empty fruit bunch; Prehydrolysis soda-anthraquinone; Enzymatic hydrolysis; Cellobiose; Pyrolysis-gas chromatography-mass spectrometry; Syringyl/guaiacyl ratio
• ISSN: 1930-2126; 1930-2126
• DOI: 10.15376/biores.12.1.183-194

Residual lignin present in alkali pulps prepared from oil palm (Elaeis guineensis) empty fruit bunch was isolated using an enzymatic method and characterized successfully by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). These pulps were prepared by soda-anthraquinone (AQ) and prehydrolysis (PH) soda-AQ cooking methods (pulp yields were 45.3 and 33.9%, respectively). Py-GC/MS of the residual lignin showed that two pyrolysis products which were indole and methylindole originating from the enzyme (contents 12 to 44%), in addition to eight pyrolysis products originating from syringyl (S) and guaiacyl (G) structure of lignin. Furthermore, palmitic acid was also detected in the residual lignin (contents 0.11 to 0.28%). The residual lignin was subjected to further purification by a cellobiose treatment method, and the quantity of enzyme present in the residual lignin was found to decrease after the treatment. Residual lignin in PH-soda-AQ pulp exhibited a higher S/G ratio (0.86 to 0.98) than that in soda-AQ pulp (0.76 to 0.97). This study showed that the contents of lignin (19 to 44%) and enzyme in enzymatically isolated lignin can be estimated by the Py-GC/MS method.