Extractability of defatted wheat germ protein and their functionalities in a deep eutectic solvent (DES)-Microwave extraction approach compared to conventional processing

Defatted wheat germ is a viable source of plant-based proteins and this could be attributed to its high protein content. In this study, protein-rich DWG fractions were precipitated from extracts obtained via conventional alkaline and novel DES-microwave extraction techniques. Protein yield, SDS-PAGE protein profile, gelation property, water/oil holding capacities, foaming capacity, emulsifying activity, emulsion stability, as well as protein solubility and digestibility were all succinctly investigated from the protein isolates. The comparative study showed 33.0 ± 0.2% and 12.5 ± 0.01% of protein recovery from DES-microwave and conventional extractions, respectively. Moreover, from the SDS-PAGE results, the DES-microwave-assisted extraction approach was just as effective as the conventional extraction method, with no evidence of protein hydrolysis or degradation. Additionally, the protein fraction extracted through the DES-microwave method exhibited higher water solubility with the formation of firmer gel structure; higher EA (50%); excellent WHC/OHC (3.892 mg H2O/mg sample; 6.410 mg oil/mg sample); good FC (75.9%), and higher D (85.03%). In comparison, the protein fraction from conventional alkaline extraction exhibited a water-holding capacity of 3.496 mg H2O/mg sample, oil holding 6.154 mg oil/mg sample, FC = 25.8%, EC = 25%, D = 78.69%). The enhanced functionalities of the DWG protein revealed DES-microwave-assisted approach as a promising technique for obtaining pure protein concentrate. This is the first study to provide insight into the functionalities of wheat germ protein using novel deep eutectic solvents (DES) via an electromagnetic-based microwaved medium.