Cascading Biorefinery of Chickpea Using Deep Eutectic Solvents for Protein Recovery and Bioethanol Production

¹ Biorefinery and Process Automation Engineering Center, Department of Chemical Process Engineering, The Sirindhorn International Thai-German Graduate School of Engineering, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
² Department of Biotechnology, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
³ Department of Biotechnology, Faculty of Agro-industry, Kasetsart University, Bangkok, Thailand

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

A cascading biorefinery strategy using deep eutectic solvents (DES) was developed for protein extraction from chickpea biomass and subsequent bioethanol production from the residual lignocellulosic material. Protein was first extracted using DES, after which the remaining biomass was further pretreated with a choline chloride:oxalic acid:glycerol (ChCl:OA:G, 1:1:2) system to enhance enzymatic hydrolysis. Pretreatment parameters were optimized using Response Surface Methodology (RSM), and the optimal conditions were identified as 6% solid loading, 122 ^oC, and 200 min. Under this optimal condition, the reducing sugar concentration reached 14.56 mg/mL. Fermentation of the hydrolysate using Saccharomyces cerevisiae resulted in an ethanol concentration of 5.92 g/L. The results showed that DES pretreatment significantly increased sugar and ethanol concentrations due to improved structural disruption and enzyme accessibility. This study demonstrates the potential of DES as a sustainable pretreatment solvent for integrated food and bioenergy production within a circular economy framework.