Ultrasound-Extracted Faba Bean Proteins: Process-Structure-Function Interplay for Superior Plant Ingredients

Faba beans have traditionally been used as animal feed and scarcely utilized in food product development. However, it is an excellent source of high-value proteins that can be extracted and employed in food systems, nutraceuticals, and as valuable starting material for developing next generation food ingredients. This research aimed to enhance the extraction efficiency and functionality of faba bean protein isolates (FBPI) through ultrasound-assisted extraction (UAE), a non-thermal green technology. This approach has a critical role in reducing levels of antinutrients commonly present in whole faba beans. In the first phase, the influence of ultrasonication time on protein yield, purity, and physicochemical properties was assessed. UAE significantly outperformed conventional alkaline–isoelectric precipitation, achieving maximum purity of 88.8% after 45min. Vicine and convicine levels were reduced (3.6–3.8 mg/g) compared with raw flour (8.8mg/g). Electrophoresis and size-exclusion HPLC confirmed structural integrity, while FTIR indicated subtle secondary structural changes. Thermal analysis showed similar denaturation temperatures (~107°C) across treatments, with minor differences in decomposition behaviour. The second phase applied a Box–Behnken Design to optimise UAE parameters. Optimised conditions yielded 92.9% protein purity and 19.8% extraction yield. The resulting FBPI exhibited improved solubility, water- and oilholding capacities, although foaming ability was slightly reduced. Structural analysis confirmed modest conformational adjustments without loss of functionality. In the final phase, the gelation, emulsifying and rheological behaviour of FBPI were benchmarked against soy and pea protein isolates. All samples showed shear-thinning flow, but FBPI displayed a distinct viscoelastic profile and stronger gel strength. Differences in FTIR spectra explained variations in gelation and rheology. Overall, UAE demonstrated clear potential as a scalable method for producing high-quality FBPI with enhanced structural and functional properties, strengthening its role in next-generation plant-based food systems.