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Enzymatic synthesis of epoxy fatty acid starch ester in ionic liquid–organic solvent mixture from vernonia oil
Author(s) -
Desalegn Tegene,
Garcia Ignacio J. Villar,
Titman Jeremy,
Licence Peter,
Diaz Isabel,
Chebude Yonas
Publication year - 2014
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.201300142
Subject(s) - crystallinity , thermogravimetric analysis , starch , fourier transform infrared spectroscopy , solvent , chemistry , thermal decomposition , ionic liquid , organic chemistry , candida antarctica , nuclear chemistry , epoxy , polymer chemistry , catalysis , lipase , chemical engineering , enzyme , engineering , crystallography
In this study, epoxy fatty acid esters of cassava starch were synthesized by reacting cassava starch with vernonia oil methyl ester (epoxy ester) using 1‐butyl‐3‐methylimidazolium hexafluorophosphate, [C 4 C 1 Im][PF 6 ] ionic liquid (IL) as a reaction medium and DMSO as co‐solvent. Lipase Candida antarctica fraction B (Novozyme 435) was used as a catalyst for the esterification reaction. In the optimized reaction conditions, a degree of substitution (DS) of 0.95 was achieved, at a reaction temperature of 40°C within 72 h of reaction time. The new cassava starch esters were characterized by infrared (FTIR), solid state NMR (CP/MAS 13 C NMR), SEM, XRD, thermogravimetric analysis (TGA), and DSC. FTIR and NMR spectroscopy analyses confirmed the successful esterification of starch and the DS was calculated to be 0.95 by titration methods. SEM and XRD studies showed that the morphology and crystallinity of native cassava starch were significantly changed upon esterification producing a continuous and amorphous material. Finally, the thermal behavior of the native and the starch vernolate was investigated using TGA and DSC techniques. The results revealed a change in the characteristic melting point and decomposition pattern of the new polymer. The onset decomposition temperature of the new starch vernolate is similar to the native form.