Molecular Dynamics Simulation Allows Mechanistic Understanding of Natural Deep Eutectic Solvents Action on Rapeseed Proteins

There is growing demand for alternative sources of nutritional protein to replace animal protein in the diet. This is driven partly by the concern over environmental sustainability of animal agriculture and partly by consumer health concerns. Animal proteins (e.g. milk and egg protein) are relatively easy to isolate and purify, whilst this is not always true for alternative proteins sources including those from agricultural co-product streams such as the press cake from oil production from oil seeds. These can require relatively harsh organic solvent conditions that may alter protein functionality. In the search for alternative, more gentle solvents, natural deep eutectic solvents (NADES) are receiving significant attention. In this study, a combination of experimental and molecular dynamics simulation studies was used to explore the efficiency of NADES made from glycerol and choline chloride and betaine and citric acid at extracting protein from rapeseed press cake. Whilst extraction with water alone gave the highest protein purity, NADES formulations were able to significantly increase the protein yield compared to both water and alkaline extraction, although at reduced purity of the extract. MD simulation highlighted that glycerol-choline chloride NADES were more efficient at disrupting protein-water interactions which may facilitate extraction. Overall, the study suggests NADES have potential as mild protein extractants, but more research is required on optimizing both the choice of components and concentration of species to maximise yield and purity of protein extracts.