Synergistic interaction between exogenous and endogenous emulsifiers and its impact on in vitro digestion of lipid in crowded medium.

Control of lipid digestibility by various food components has received great attention in recent decades. However, there is limited literature on investigating the synergistic effect of exogenous emulsifiers and endogenous sodium cholate (SC) on lipid digestion in a simulated physiological crowded medium. In this work, the synergistic interaction of Tween80 and SC according to the regular solution theory, and the hydrolysis of lipid emulsions containing tricaprylin, glyceryltrioleate or soybean oil in crowding medium was studied. The results show that emulsions stabilized by a combination of Tween80 and SC showed higher digestion rate and transformation than those with Tween80 or SC. The digestion rate could be increased by polyethylene glycols (PEGn) with varying crowding degree. The denaturation temperature of the lipase was increased in macromolecular crowded medium. This work allows for better understanding of the interaction between the amphiphiles and the macromolecular crowding effect on lipase digestion in the physiological environment.

Difference in Binding of Long- and Medium-Chain Fatty Acids with Serum Albumin: The Role of Macromolecular Crowding Effect.

Fatty acids (FAs) are transported by serum albumin in plasma. Studies have been undertaken to address the binding of MCFAs or LCFAs to human plasma albumin (HPA) and bovine serum albumin (BSA) by characterizing the binding affinities. Previous research on FA binding to serum albumin was usually performed in dilute solutions that are not sufficiently concentrated for the interpretation of the significance of the results under normal physiological conditions. How macromolecular crowded media affect fatty acids and bovine serum albumin (BSA) binding remains unknown. In this article, we investigated the mechanism of FA-BSA binding in a polyethylene glycol crowding environment by using thermodynamic and spectroscopic methods. Molecular crowding increased the binding constant for saturated medium-chain fatty acids (MCFAs) but significantly decreased the binding constant for unsaturated long-chain FAs. The binding sites tended to increase in all the cases. Further investigation revealed that crowding media might loosen the structure of BSA, facilitating MCFA-BSA binding. This research is useful for understanding the transportation of FAs by BSA under physiological conditions and may also help to control digestion by the eventual incorporation of macromolecular crowding agents into food formulations.