Modulating digestion by composite interfacial layer in structured oil-in-water emulsions

Abstract

Oleogels were applied as the lipid phase in oil-in-water (O/W) emulsions as a strategy to modulate in vitro lipid digestion. Lipid phase was structured with fruit wax (FW) or FW combined with lecithin (phosphatidylcholine-rich fraction) (FWLEC), while emulsifiers with low (Tween 80- T80) or high (whey protein isolate- WPI) molecular weight emulsifiers were added in the aqueous phase. All emulsions showed comparable mean droplet size (1.2–1.5 µm). The combined effect of emulsifiers (T80 and WPI) and oleogelators (FW and LEC) influenced interfacial behavior, modifying the profile of surface pressure over time and interfacial elasticity (0.9–22.7 mN/m). After the simulation of gastric conditions, WPI emulsions yielded larger droplet sizes, lower absolute values of ζ-potential and extensive aggregation of droplets compared to T80-stabilized emulsions. On the other hand, intestinal lipolysis was highly influenced by the presence of oleogelators and emulsifiers forming the interface of the droplets (32.9–65.1% of free fatty acids released). Interestingly, emulsified FWLEC oleogels stabilized by WPI led to reduced lipolysis, showing the lowest rate and extent of free fatty acids released. This outcome shed light on designing mixed interfaces for lipid digestion control purposes.