Dry fractionation of faba bean (Vicia faba L. var. minor): An optimized procedure via air-classification

The growing global demand for sustainable and nutritious protein sources has intensified interest in legumes such as faba bean (Vicia faba L.), valued for their high protein content, agronomic adaptability, and environmental benefits. However, conventional wet extraction methods are resource- and energy-intensive and often compromise protein functionality. Dry fractionation presents a promising alternative yet remains underexplored for Vicia faba L. var. minor. This study developed and evaluated a novel dry fractionation approach combining ultrafine micronization with three-stage air-classification to produce protein-rich (PRF) and starch-rich (SRF) fractions from dehulled faba bean flour. Micronization effectively reduced the median particle size D50 of dehulled flour, from 15.54 to 9.60 μm, facilitating sharper aerodynamic separation. Subsequent classification at decreasing wheel speeds (9000, 7000, and 5000 rpm) yielded PRFs with protein contents up to 71.98 %. Notably, PRFs exhibited fine particle sizes (D50 < 5.5 μm), consistent with the dimensions of protein bodies, supporting selective concentration and improved dispersion potential. The PRFs were enriched in key amino acids, particularly lysine and glutamic acid, while amino acid-to-protein ratios remained stable, with only minor statistically significant changes for some amino acids (e.g., aspartic and glutamic acid). However, protein yields remained below 18 %, with substantial retention in SRFs, highlighting the typical purity-yield trade-off in dry fractionation. Despite this limitation, the process is scalable, solvent-free, and environmentally favorable. It enables the valorization of both PRFs and SRFs and contributes to the development of sustainable, high-protein ingredients aligned with circular and climate-resilient food systems.