This review discusses different protein sources and their role in human nutrition, focusing on their structure, digestibility, and bioavailability. Plant-based proteins, such as those found in legumes, nuts, and seeds, may contain anti-nutritional factors that impact their bioavailability apart from structural and compositional differences from animal proteins. Animal proteins are generally highly digestible and nutritionally superior to plant proteins, with higher amino acid bioavailability. Alternative protein sources are also processed in different ways, which can alter their structure and nutritional value, which is also discussed.

The faba bean (Vicia faba L.) is emerging as a sustainable protein source, with up to 32% protein and a high fibre content, comparable to that of mainstream plant proteins such as peas. This study assessed the physicochemical, thermal, techno-functional, and nutritional properties of faba bean flour (FBF), protein concentrates (FBPC), and protein isolates (FBPI). It aimed to determine whether protein functionality in faba bean derivatives is governed by matrix composition and processing methods or by protein purity alone. The unrefined and semi-refined fractions (FBF and FBPC) demonstrated superior solubility, stronger gelation, and enhanced emulsification and foaming stabilities, attributed to water-soluble albumins, native polysaccharides, and intact protein structures that promote intermolecular interactions. In contrast, FBPI showed greater water- and oil-holding capacities, but its reduced solubility and poor gel strength likely resulted from denaturation and the loss of functional components during processing. Thermal analysis further supported these findings, with higher denaturation temperatures in FBF indicating better stability. Despite increased essential amino acids with refining, valuable water-soluble albumins and non-essential amino acids were lost. While cultivar and processing differences may have contributed to the observed variations among commercially sourced faba bean derivatives, this study demonstrates that functionality extends beyond protein purity, highlighting the benefits of unrefined and semi-refined faba bean ingredients across various food applications.