Structural, functional properties and immunomodulatory activity of isolated Inca peanut (Plukenetia volubilis L.) seed albumin fraction.

This work aimed to determine the structural, functional properties and immunomodulatory activity of an albumin fraction isolated from Inca peanut seed (AF-IPS). Structural characterization revealed that AF-IPS contains two polypeptides with molecular weight ranges of 25-45 and 10-15 kDa. AF-IPS is mainly composed of α-helix, β-sheet, and β-turn secondary structures. Differential scanning calorimetry analysis indicated that the denaturation temperature of AF-IPS at room temperature is 101.93 °C. AF-IPS possessed excellent protein solubility (63.0%), water holding capacity (1.59 g/g), foaming (350.2%) and emulsifying (13.0 mL/g) ability. Heat treatment improved protein solubility, oil holding capacity, and foaming and emulsifying ability. AF-IPS exhibited immunomodulatory activity by stimulating the proliferation and enhancing the TNF-α secretion of splenic lymphocytes, and through increasing the cellular lysosomal enzyme and pinocytic activities, and by moderately promoting the NO and H2O2 production of RAW264.7 cells. Our findings indicated that AF-IPS has potential applications in functional and pharmaceuticals foods.