Establishment of an Aqueous PEG 200-Based Deep Eutectic Solvent Extraction and Enrichment Method for Pumpkin (Cucurbita moschata) Seed Protein

A novel approach for ultrasound-microwave synergistic extraction (UMSE) of pumpkin seed protein was developed using aqueous poly (ethylene glycol) (PEG 200)-based deep eutectic solvent (DES) as a green extraction medium. Key factors controlling the extraction and optimal operating conditions were optimized by combining the one variable at a time and response surface methodology. Results showed that the PEG 200 as a hydrogen bond donor combined with choline chloride as a typical hydrogen bond acceptor had a highest extraction efficiency among different solvents. The optimal extraction parameters were optimized as follows: PEG 200-based DES concentration, 28% w/w; solid to liquid ratio, 28 g mL(-1); microwave power, 140 W; and extraction temperature, 43 degrees C. Under the optimal parameters, the actual extraction yield was 93.95 +/- 0.23% (n = 3). The precipitation rate of pumpkin seed protein was 97.97% with a precipitation time of only 4 min by using an isoelectric point-ethanol-PEG 200 DES ternary co-precipitation method. Overall, this integrated method of PEG 200-based DES and UMSE exhibits a powerful tool for the rapid and efficient extraction of pumpkin seed protein.