Structural, physicochemical, and functional properties of white and blue lupin vicilin and legumin fractions

The aim of this study was to isolate the vicilin and legumin protein fractions of lupin seeds and determine their physicochemical and functional properties. White lupin vicilin (WLVL) exhibited a significantly higher methionine + cysteine content (2.92 g/100 g protein) than the legumin fractions, with a corresponding amino acid score of 127 %. Blue lupin vicilin (BLVL) exhibited high surface hydrophobicity (459.12), whereas the blue lupin legumin (BLLEG) fraction had a high least gelation concentration (18 %). All fractions exhibited U-shaped solubility curves, with minimum values at pH 5, while BLLEG showed superior in vitro protein digestibility (87.47 %). BLVL demonstrated high emulsifying properties across all pH values, maintaining small droplet sizes (7-9 μm) and high stability (95-100 %). BLVL also exhibited superior foaming capacity (75-85 %), whereas WLVL showed excellent foam stability (65-80 %). These findings revealed significant species-specific and fraction-specific differences in lupin globulins, with BLVL emerging as a promising ingredient for food applications.