Gastric conditions control both the evolution of the organization of protein-stabilized emulsions and the kinetic of lipolysis during in vitro digestion

During digestion, lipids undergo modifications of their colloidal and molecular structures, which depend on the digestive conditions and the composition of the digestive juices. The aim of this work was to evaluate whether gastric pH and pepsin modulate the colloidal evolution and the bioacessibility of fatty acids of an oil-in-water emulsion stabilized by a protein during in vitro digestion. The fate of BSA-stabilized rapeseed oil-in-water emulsion during gastric phase at pH 2.5 or 4.0 with or without pepsin and its consequences on intestinal lipolysis was measured in the simulated gastric and duodenal conditions. The pH had limited impact but pepsin favoured flocculation and coalescence of the droplets, modulating the early stage of lipolysis but not its final extent.