Digestive behavior of lactoferrin-pectin electrostatic complexes: Effect of pectin esterification degree on the...

Lactoferrin (LF) exhibits a wide range of biological activities. However, its digestive instability has limited its bioavailability. To enhance the digestive stability of LF, 3 pectins (PEC) with different degrees of esterification (DE) were used to form soluble LF-PEC complexes at pH 7 at 1:1 volume ratio. Changes in physicochemical and functional properties of complexes were systematically analyzed during simulated gastrointestinal digestion. These complexes conferred protective effects on LF during the gastric phase, with the degree of protection varying depending on the DE of the PEC. However, no significant protective effect was observed during the intestinal digestion phase. Low-methoxyl PEC (DE = 30%) demonstrated a superior protective effect compared with high-methoxyl PEC (DE ≤62% and DE ≥68%). During gastric digestion, LF-PEC complexes exhibited lower release of total amino acids and free amino groups, together with a relatively higher distribution of molecular weight fragments on SDS-PAGE, compared with LF alone. The reduced radical scavenging capacity of the complexes further suggested attenuated proteolytic generation of antioxidant peptides. Molecular docking studies supported the notion that PEC partially hinders LF hydrolysis in the gastric environment, with DE-dependent differences among PEC. These findings demonstrate that complexation with PEC significantly reduces the gastric degradation of LF, supporting its potential use in functional foods.