Abstract: In order to study the effect of liposomes on gastric oxidative stress and the lipolysis kinetics of liposomes during gastric and small intestinal digestion, an in vitro infant gastrointestinal system was established, with its adult counterpart as control. Results showed that the average diameter of liposomes was significantly decreased and the negative zeta potential was increased after digestion. The oxidation degree of liposomal membrane, which was characterized by thiobarbituric acid reactive substances (TBARS), significantly increased after gastric digestion. Free fatty acids were released continuously during stimulated intestinal digestion, and the rate of lipolysis in the infant gastrointestinal system (38%) was obviously higher than that in the adult one (80%). The release profiles fitted first-order kinetics. Moreover, Fourier transform infrared spectroscopy (FT-IR) showed that the peaks of characteristic groups in phospholipids (C=O, P=O and ?CH2) changed after digestion, and the liposomal membrane in the infant gastrointestinal system was damaged less seriously than in the adult one. This study can provide a theoretical guidance for liposomes as a nutrient carrier in infant formula.

Key words: liposome, in vitro digestion, infant, membrane structure, stability