Extraction of protein from Alphitobius diaperinus larvae (lesser mealworm) powder using tailored bio-based ionic liquids

Abstract

The present investigation aims to optimize a protein extraction process from Alphitobius diaperinus (lesser mealworm) larvae using designer ionic liquids. Three ionic liquids were synthesized using choline esters of C₈, C₁₀, and C₁₂ chains, with potassium lactate as the anion. Their purity was confirmed via NMR spectroscopy and elemental analysis, indicating their suitability for extracting protein from lesser mealworm insect powder. All analyses were performed in triplicate and the results were evaluated by an ANOVA, extraction was initially performed by mechanical shaking followed by ultrasound. The results revealed protein extraction yields ranging from 46.4 % ± 1.7–64.7 % ± 2.1, with a protein content between 53.3 % ± 1.8 and 63.3 % ± 2.4, as verified by FTIR analysis. In particular, FTIR spectra exhibited consistent signals across samples, with absorption peaks at 1600–1700 cm⁻¹ assigned to the amide I band and peaks at 1500–1600 cm⁻¹ attributed to the N-H in the amide II band. Further investigations were conducted to assess ± the influence of particle size on the extraction process, revealing that a particle size of 300 µm yielded the best extraction results. Importantly, analysis via ¹H NMR demonstrated that the structure of the ionic liquid remained unchanged throughout the extraction process, validating its potential for reuse in subsequent extractions. Despite the good results obtained in the extractions, there is still much work to be done. Future research must focus on improving extraction yields and the purity of the precipitates by optimising operating conditions such as time, temperatures, and ratios.