Dietary interference on the oxidation and hydrolysis of liposomes during in vitro digestion

Enhancement of Astaxanthin Bioaccessibility by Encapsulation in Liposomes: An In Vitro Study

Astaxanthin was encapsulated in liposomes by a thin layer dispersion and ultrasound method using soybean phospholipid. The digestion properties of liposomes for encapsulating astaxanthin were investigated in light of particle size, size distribution, zeta potential, and microstructure during in vitro digestion as a function of time. These results exhibited that the average particle size increased gradually with liposomal vesicles retained round shapes and a fairly uniform distribution after passage through the simulated gastric fluid digestion. The result revealed that astaxanthin-loaded liposomes were stable in low pH conditions. It was also found that the mixed micelles formed in a simulated intestinal fluid. The zeta potential of astaxanthin-loaded liposomes had a decrease in negativity after digestion. In comparison with free astaxanthin, there was an appreciable increase in the bioaccessibility of astaxanthin after encapsulation in liposomes. This enhancement can be attributed to more soluble astaxanthin in the mixed micelles for astaxanthin-loaded liposomes. It indicated that the barrier of the liposomal bilayer could inhibit astaxanthin fading and leaking after encapsulation in liposomes. These results provide useful information for designing more stable delivery systems in the gastrointestinal tract and improving the bioaccessibility of lipophilic nutraceuticals.

Effect of emulsifiers on linseed oil emulsion structure, lipolysis and oxidation during in vitro digestion

Health benefits have been associated with the consumption of omega-3 polyunsaturated fatty acids (PUFA). Linseed oil is rich in long chain omega-3 PUFA, but can generate toxic compounds due to its high susceptibility to oxidation. The nature of the emulsifier can affect both lipolysis and oxidation during digestion since these phenomena occur at the oil-water interface. The objective of this study was to compare the effect of low-molecular weight surfactants (cetyltrimethylammonium bromide (CTAB), Citrem), protein (sodium caseinate, fish gelatin) and polysaccharides (gum arabic, modified starch) on the structure of linseed oil emulsions, lipolysis and formation of reactive oxidation species during in vitro digestion. The emulsion stabilized with Citrem underwent extensive coalescence in the gastric phase, which strongly decreased the extent of lipid digestion and reduced the formation of oxidation markers relative to other emulsions. Emulsions stabilized by proteins and modified starch showed aggregation with partial coalescence in the gastric phase, but protein-stabilized emulsions showed better resistance to oxidation. This study shows that emulsifier properties affect the susceptibility of the emulsion to aggregation and coalescence in the gastrointestinal environment, and strongly influence the extent of lipid digestion and the formation of reactive oxidation products. These findings point out the importance of the choice of the emulsifier to control the lipid digestibility and the protection of sensible lipids thus promoting optimal nutritional properties in omega-3-enriched foods.