Legume proteins are a promising source in the current protein transition. Growing legumes is environmentally friendly, as they have a low carbon footprint, high water efficiency, and nitrogen fixation ability. Legumes can be processed into different protein enriched ingredients. A protein concentrate (typically 50-70 wt.% protein) is commonly obtained through dry fractionation, whilst a protein isolate (typically >70 wt.% protein) requires wet fractionation. Several types of wet fractionation exist, such as alkaline or acid extraction followed by isoelectric precipitation or ultrafiltration and salt extraction. Wet fractionation is less sustainable than dry processing, but produces an ingredient with a higher protein content. Protein ingredients from pea have already been widely studied, whereas other promising sources such as faba bean have been emerging more recently. It has notably been shown that the processing itinerary and conditions applied affect the composition and functional properties of pea and faba bean protein ingredients. Often, differences in the functional properties are ascribed to the state of the protein molecules. For instance, dry fractionated concentrates have been found to retain a native protein structure, whereas harsher conditions applied during wet fractionation, in particular via isoelectric precipitation, induce protein denaturation. Therefore, protein ingredients obtained through isoelectric precipitation have been found to have reduced solubility and emulsifying properties compared to those of dry fractionated or ultra-filtrated ingredients. Yet, current research lacks a comprehensive characterization of the protein ingredients, especially regarding their non-protein components and the associated effects on ingredient functionality. Lipids present in the seeds, in particular, can accumulate during the protein fractionation process and modulate the functional properties of the ingredient. In addition, anti-nutritional compounds can be preferentially removed or enriched depending on the applied process. Therefore, further research is required to fully understand the complex relationship between protein processing, ingredient composition and ingredient functionality.