Steady and cyclic recovery of potato protein from starch waste via tailored deep eutectic solvent system

Abstract

Tons of starch wastewater produced during potato processing causes sever environmental problem, but can serve as a sustainable and promising source of bioactive proteins for food applications. However, potato protein recovery faces several challenges such as easy loss of bioactivity, extensive reliance on organic and potentially toxic reagents, and low cost-effectiveness. In this work, we explored the potential of deep eutectic solvent (DES) as green approach to achieve efficient protein recovery via high-throughput screened DES customization and one-step cyclic recovery system design. To address the issue of unclear protein structure that hinders extraction efficiency using DES, the solvent accessible surface area was firstly introduced to provide a more precise and detailed description of the protein based on COSMO-RS molecular descriptors, and 9 out of 10,687 compounds were found as customized DES candidates. Among them, for the first time, polyethylene glycol (PEG) and mannose were found to be protective DES partners, which could retain at least 90% of patatin activity by decelerating the surrounding molecules and maintaining the hydration shell, 10 times and 1.5 times higher than the traditional acid-heat method and the conventional DES, respectively. In addition, the PEG-mannose DES was formed upon vacuum distillation of wastewater, during which patatin was selectively entrapped and further separated out using another batch of wastewater as anti-solvent before next distillation. This process allows for the cyclic use of DES and demonstrates a green and scalable approach for steady-state recovery of bioactive proteins from industrial starch wastewater.