Protein Extraction from Alphitobius diaperinus Using Choline-based Amino Acid Ionic Liquids

Abstract The accelerated global increase in sustainable protein sources has driven the consumption of insects as a viable alternative in this regard. The larva of Alphitobius diaperinus stands out for its high protein content. This study evaluated a protein extraction process using bio-based ionic liquids, specifically choline-arginine and choline-glycine. Efficiency of choline based ionic liquids was compared with conventional alkaline extraction method. Both ionic liquids were synthesized by acid–base neutralization and characterized by nuclear magnetic resonance spectroscopy (NMR). Extraction was optimized by varying temperature and biomass:IL ratio. The purity of the extracted protein powder was assessed by Fourier transform infrared spectroscopy (FTIR) and Matrix-Assisted Laser Desorption/Ionization (MALDI-TOF), and the yields were quantified using the Lowry method. The choline-arginine ionic liquid at 50ºC and with a ratio of 1:10 showed the highest efficiency, achieving a protein recovery yield of 80.0%. MALDI-TOF analysis revealed the presence of bioactive peptides, suggesting high functional potential. The recovery of the ionic liquids demonstrated that they retain their structural integrity, allowing their reusability in subsequent cycles. Ionic liquid recovery was achieved with high efficiency (≥ 94.7%) and structural integrity was confirmed by 1H-NMR spectroscopy, TGA and FTIR, demonstrating excellent reusability potential for subsequent extraction cicles. This work validates the use of ionic liquids as an efficient and environmentally friendly alternative for protein extraction from entomological biomass.