The Effect of Tripalmitin Crystallinity on Emulsion Lipid In Vitro Digestion

The purpose of this study was to determine the impact of TAG crystallinity on digestibility using undercooled (Liquid-Emulsion) and crystalline (Solid-Emulsion) particles exposed to an in vitro model simulating upper gastrointestinal (GIT) digestive conditions. 10 wt% tripalmitin oil-in-water emulsions (d3,2~0.115 nm) with 0.9 wt% sodium dodecyl sulfate (SDS) were prepared. The Solid-Emulsion sample demonstrated complex melting behaviour, was predominantly in the β polymorph and contained a heterogeneous mixture of platelets, rods and spheres. Samples were exposed to conditions representative of gastric and duodenal conditions. In vitro duodenal lipolysis was more extensive for the Liquid-Emulsion (P<0.05). Gastric exposure (at pH 2 but not at 7) of the spherical Liquid-Emulsion induced partial crystallization (β) and coalescence and led to the presence of one melting peak (i.e. 62.1 ± 0.2 °C, β) in the Solid-Emulsion. SDS induced lipid crystallization and higher surface loads were observed for the Solid-Emulsion and for the Liquid-Emulsion at lower pH. Therefore, lipid droplet physical state impacted and was impacted by digestion.