Interactions between Pluronics (F127 and F68) and Bile Salts (NaTDC) in the Aqueous Phase and the Interface of Oil-in-Water Emulsions

Pluronics are being introduced in food research in order to delay lipid digestion, with the length of hydrophilic and hydrophobic chains playing an important role in the rate of such a process. Since bile salts play a crucial role in the lipid digestion process, the aim of this work is to analyze the interactions between Pluronic F127 or F68 and the bile salt NaTDC when the latter is added at physiological concentrations. These interactions are studied at the Pluronic-covered oil–water interface and in the aqueous phase of Pluronic-stabilized emulsions. This work has been carried out with techniques such as differential scanning calorimetry, interfacial tension, dilatational rheology, and scanning electron microscopy. As a result, Pluronic F127 was shown to be more resistant to displacement by bile salt than F68 at the oil–water interface due to the larger steric hindrance and interfacial coverage provided. In addition, Pluronics have the ability to compete for the oil–water interface and interact in the bulk with the bile salt. Concretely, Pluronic F127 seems to interact with more molecules of bile salt in the bulk, thus hindering their adsorption onto the oil–water interface. As a conclusion, Pluronic F127 affects to a larger extent the ability of bile salt to promote the further cascade of lipolysis in the presence of lipase owing to a combination of interfacial and bulk events.