Sustainable extraction technology using Deep Eutectic Solvents for producing fava bean protein isolates with improved functionalities

The fava bean is a nutritionally rich protein source, making it an ideal choice for producing protein ingredients. The limitations of conventional plant protein extraction methods have driven increasing interest in novel, sustainable green extraction technologies. Therefore, the main objective of this research study was to develop a novel protein extraction method using Deep Eutectic Solvents (DES) for producing fava bean protein ingredients with improved functionalities. First, the DES system was optimized for the protein extraction variables using the response surface methodology (RSM). The optimum conditions achieved indicated that the DES could produce a significantly higher protein yield (~65%) with similar protein content (~92%) to the conventional alkaline method (AE). It was revealed that DES extraction was also less prone to protein denaturation than AE. Owing to these properties of DES-extracted fava bean protein isolates (DES-FBPI), the functional properties, solubility, and emulsifying and foaming properties were greatly improved. Interestingly, the DES method produced high-quality proteins with significantly higher (>75%) protein digestibility-corrected amino acid score (PDCAAS), compared to the conventional methods. Moreover, the integrated approach, including ultrasonication and enzymatic pre-treatment-assisted DES protein extraction, further showed a significant increase in protein yield with improved functionality. Although DES is highly viscous, the addition of water in the DES system (0-100% wt%) demonstrated significantly reduced viscosity, thus significantly increasing protein yield. The alteration of physicochemical and structural changes of DES induced by the water substitution led to significant differences in the structure-functional properties of the extracted proteins, tailored to a specific food application. From the food application perspective, the behavior of fava bean proteins in the DES system is crucial when determining protein functionality, including gelation. In particular, the gelling capacity of DES-FBPI was a distinguishable characteristic, producing a strong, firm gel comparable to commercially produced soy proteins. Hence, DES extraction offers a valuable opportunity to replace soy-based foods with fava bean proteins as a potential strategy to reduce soy allergenicity. Overall, DES extraction presents a viable alternative to conventional methods, offering green benefits with potential scalability at the industrial level to upgrade the utilization of fava beans in value-added food formulations.