Unveiling structure-function relationships in mung bean proteins: A comparative study of albumin- and globulin-rich fractions.

The production of mung bean protein isolates (MBPI) generates an acid-soluble byproduct enriched in albumins that remains largely underutilized. This study recovered and characterized the acid-soluble (MBP-AS) and albumin-rich (MBP-AR) fractions from MBPI processing and compared their structural and functional properties with those of globulin-rich MBPI across different pH conditions. Ultrafiltration and dialysis increased the protein purity of MBP-AR to 86.8%, with albumin-2-like protein (~30 kDa) identified as the predominant component. Both albumin fractions exhibited substantially higher solubility over pH 3-10 and superior foaming capacity of 446-641% when compared to the 77-410% for MBPI. FTIR analysis revealed a higher α-helical content of 20.9% and pronounced carbohydrate-associated bands (890-1183 cm-1) in MBP-AS, whereas dialysis effectively removed carbohydrate components from MBP-AR. Microdifferential scanning calorimetry showed that MBPI possessed greater thermal stability (85.5-86.9 °C) than the albumin-rich fractions (73.4-74.2 °C). MBP-AR also underwent gelation at relatively low temperatures (55-64 °C) and formed firm, elastic gels across pH 5.8-7.8 with storage moduli (G') values of 0.20-0.22 kPa, while exhibiting less pH-dependent functionality than MBPI. The enhanced flexibility, solubility, and gelation behavior of MBP-AR highlights its potential as a versatile ingredient for foamed and structured plant-based foods. This study provides the first comprehensive comparison of mung bean albumin- and globulin-rich fractions and demonstrates a value-added strategy for utilization of a currently underexploited protein stream.