| DOI: 10.29090/psa.2025.01.24.2034 | Pharm Sci Asia 2025; 52(1), 87-99 |
Effect of Temperature on Lignin Extraction from Cocoa Shells using Deep Eutectic Solvent: Optimization and CharacterizationSupika Arkhasuwan1, Tasana Pitaksuteepong1,2,*
1 Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand
2
Center of Excellence for Innovation in Chemistry, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand
Lignin has been reported as a natural UV protectant due to its chemical structures. Deep Eutectic Solvent (DES) has shown potential for the lignin extraction method. This research aimed to study the effect of temperatures on the lignin extraction using DES (composed of choline chloride and lactic acid) from Theobroma cacao L. c.v. I.M.1, in which the employed parts were cocoa pod shells (CPS) and cocoa bean shells (CBS). The extracts were determined for %yield and lignocellulosic compositions (i.e., lignin, cellulose, and hemicellulose). The compositions were evaluated using TAPPI T222-om-88, acid chlorite, and TAPPI T203-om-88 methods. Fourier Transform Infrared Spectroscopy (FT-IR) was employed to characterize the chemical structure of lignin. The investigation found that the extracts from both biomasses had a color ranging from dark brown to black. The extracts from CBS (CBS-LE-T) prepared at 80 °C, 120 °C, and 150 °C had lignin contents of 80.0±2.1%, 79.7±3.4%, and 76.4±2.1%, respectively. These values were greater than those of the extracts from CPS. Consequently, more research was done on the CBS-LE-T extracts. Yield increased with elevated temperatures: 80 °C (4.5±0.7%), 120 °C (17.4±3.9%), and 150 °C (19.7±3.7%). The contents of cellulose and hemicellulose were 0.6±0.1% to 1.0±0.9% and 4.3±2.3% to 6.3±2.5%, respectively. FT-IR spectra illustrated the functional groups of lignin structure including hydroxy group and aromatic rings. Hence, DES possessed the efficient ability to extract lignin from biomass. Higher lignin content was provided by CBS, and 120 °C was shown to be the optimal temperature for both a high yield and lignin content from CBS.
Keyword:
Lignin extraction; Deep Eutectic Solvent (DES); Cocoa pod shells (CPS); Cocoa bean shells (CBS); The potential UV protective application of lignin; Natural UV protectant; Biomass sources
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