A switchable-solvent-based extraction and recovery of protein from Acheta domesticus for sustainable food applications

Traditional alkaline extraction of alternative proteins often results in irreversible molecular degradation and significant environmental burdens due to wastewater salinity and high energy demands. This study optimizes a Switchable Composite Extractant (SCE) a mixture of ethanol, propylene glycol, and water—for the efficient extraction and recovery of protein from Acheta domesticus powder. Exploiting temperature- and pH-responsive properties, the SCE enables protein dissolution and precipitation while bypassing the energy-intensive distillation bottleneck characteristic of conventional organic solvent recovery. Optimization followed a two-step approach: first, determining the ideal solid-to-liquid ratio (1,20 w/v); second, adjusting extraction and precipitation pH values in conjunction with temperature. A multi-criteria screening of the extraction window (pH 9, 10, and 11) was performed using a Joint Standard Deviation analysis to identify the point of maximum process stability. Results indicated that while higher pH levels offered similar solubility, pH 9 provided superior statistical control and recovery efficiency. Subsequent refinement identified pH 4.3 as the optimal point for protein recovery. Under these optimized conditions, a total recovery efficiency of 47.8% was achieved. Comparative analysis with a conventional alkaline extraction method, supported by SDS-PAGE, indicated that the SCE method better preserved protein integrity, showing distinct bands for key cricket proteins while the conventional method resulted in significant degradation. Furthermore, the techno-functional properties of the SCE-extracted protein, including water absorption capacity (4.3 ± 0.03 mL/g) and fat absorption capacity (3.78 ± 0.13 g/g), demonstrate its potential for various food applications. These findings suggest that the SCE-based process offers a robust, high-fidelity alternative to traditional protein isolation, facilitating sustainable, high-quality insect-based food ingredients.