Delaying lipid digestion through steric surfactant Pluronic F68: A novel in vitro approach

The objective of this study was to investigate and compare the lipolysis rate of emulsions stabilized with two surfactants of a markedly different nature: an ionic mixture of phospholipids and the almost purely steric surfactant Pluronic F68. We have studied emulsions stabilized with only one of them, and also with mixtures with different proportions of these two emulsifiers. The impact on lipolysis of the addition of different amounts of β-casein, which is capable of forming thick interfacial layers, was also investigated. To carry out this study, we propose an alternative method to analyze the digestion of emulsions in complex media, which relies on the changes in backscattered light monitored in time by means of a Turbiscan. Our results show that the steric emulsifier is considerably more effective on delaying the digestion of the emulsions than the ionic one. Besides, it is possible to speed up or slow down the lipolysis by varying the proportion between steric and ionic emulsifiers, and therefore to influence the absorption of lipids and/or hydrophobic compounds dissolved on them. β-casein is not able to delay lipolysis under duodenal conditions, since it is easily cleaved by proteases and displaced by endogenous bile salts.