Relation between in vitro lipid digestion and β-carotene bioaccessibility in β-carotene-enriched emulsions with different concentrations of l-α-phosphatidylcholine

- Incorporation of lipids into micelles reached maximum.
- Incorporation of lipids is independent on (used) phosphatidylcholine concentration.
- Higher phosphatidylcholine concentration leads to higher β-carotene bioaccessibility.
- No straight link between incorporation of lipids and incorporation of β-carotene

In view of consumer health, it is desirable to promote the bioaccessibility of lipid-soluble compounds like carotenoids, while limiting the lipid intake. The objective of this work was to examine the relation between in vitro lipid digestion and β-carotene bioaccessibility of carrot-based model food emulsions containing water, 5% olive oil enriched with β-carotene (from carrots) and different concentrations (1-2-3-4%) of l-α-phosphatidylcholine (PHC), as an emulsifier. The lipid digestion (hydrolysis of triacylglycerols (TAGS) and incorporation of free fatty acids (FFAs) and monoacylglycerols (MAGs) in the micelles) and the β-carotene bioaccessibility (incorporation of β-carotene in the micelles) were studied after an in vitro digestion procedure wherein the stomach phase was mimicked for 2.0 h (37 °C) and the small intestinal phase was mimicked for 1.0 h, 1.5 h and 2.0 h (37 °C) (both end-over-end rotations). As a consequence, not only the influence of the emulsifier concentration, but also the influence of the duration in the small intestinal phase was investigated in this study. The oil droplet size distributions of the emulsions at different stages of digestion were shown to be dependent on the phosphatidylcholine concentration, but independent on the duration in the small intestinal phase (1.0 h-2.0 h). Furthermore, all TAGs were already hydrolysed into FFAs and MAGs after 1.0 h small intestinal phase and the incorporation of FFAs and MAGs into micelles seemed to reach a maximum for all emulsions (approximately 26.5%), independent on the phoshpatidylcholine concentration and thus on the particle size distributions. Finally, the β-carotene bioaccessibility increased with increasing phosphatidylcholine concentration, ranging from 33.2% to 79.8% for a 1% and 4% PHC emulsion respectively. No significant differences in β-carotene bioaccessibility were however noticed for the different durations in the small intestinal phase tested. In conclusion, a higher phosphatidylcholine concentration in emulsions leads to higher β-carotene bioaccessibility while the incorporation of lipids into micelles did not increase.