Proximate, functional, and structural properties of protein isolate from undehulled, dehulled and defatted broad bean (Vicia faba).

Dehulling and defatting are conventional practices in the production of high-protein ingredients from oil seeds and pulses. However, it is unclear how crucial these steps are during pulse protein isolation. This study aimed to elucidate the role of dehulling and defatting in extracting protein from broad beans using alkali/isoelectric precipitation. It investigates their impact on the yield, protein purity, and functional and structural properties of the resulting isolates. Flour samples that were undehulled and those that were dehulled and defatted exhibited a similar protein content of approximately 28%, whereas the dehulled but undefatted flour had a higher protein content of approximately 31% (dry weight basis). Isolated protein showed significant (p < 0.05) variation, notably increased protein purity. Functional properties, such as water absorption capacity, oil absorption capacity, foaming, and emulsion capacity and stability, showed no significant differences (p < 0.05) among the isolates. This suggests that the flours are likely to behave similarly when used in food systems. Proximate composition data were similar across the samples. In terms of structure, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis analysis showed similar molecular weight distribution (22-75KDa) in the protein under both reducing and non-reducing conditions. The results of this study suggest that dehulling and defatting steps in protein isolation from broad beans and perhaps other pulses with low-fat content (< 10%) may not be necessary, depending on the intended end use of the protein isolate. Additionally, omitting these solvent-intensive processes could reduce the time, cost, health, and environmental risks associated with protein isolation. Studies are ongoing to determine the nutritional composition, including amino acid profiles and digestibility, as well as the thermal properties of the isolates.