The relation between in vitro ß-carotene bioaccessibility and lipid digestion: Influence of the structural build-up of plant-based emulsions

Vegetable-based foods such as soups and sauces, are good sources of water, fibers (e.g. pectin), micronutrients and lipids. In foods, lipids are often considered as negative since an excess uptake of lipids is linked with a risk of obesity. It should however be noted that lipids are important macronutrients providing energy and essential fatty acids and facilitating the uptake of lipid soluble micronutrients such as carotenoids. The general objective of this PhD was to gain more insight in the relation between in vitro β-carotene bioaccessibility and lipid digestion and to understand the specific role of the structural build-up of plant-based emulsions in β-carotene bioaccessibility and lipid digestion. To reach these objectives, all experimental chapters studied the influence of different emulsifiers in an oil-in-water emulsion containing 5% β-carotene enriched olive oil (no natural barriers such as chromoplast membrane and/or cell wall). The emulsifiers used were citrus pectin (CP) (added in a concentration of 1% or 2%, with a degree of methyl-esterification (DM) of 14%, 30%, 57%, 66% or 99%), sugar beet pectin (added in a concentration of 1% with a DM of 32% or 58%), L-α-phosphatidylcholine (added in different concentrations: 1%, 2%, 3% or 4%), or a combination of citrus pectin and phosphatidylcholine. Based on the results, no general relation was found between the in vitro β-carotene bioaccessibility and lipid digestion. It seems that the type, the amount and the surface activity of the present emulsifiers are determining which compounds can be incorporated into the micelles. The DM and concentration of citrus pectin were influencing the micellar incorporation of both β-carotene and lipids, whereas the DM of sugar beet pectin was not. Probably, in this type of pectin, the other pectin properties are more important than the DM. By increasing the phosphatidylcholine concentration, the lipid micellar incorporation remained whereas the β-carotene bioaccessibility increased. This lead to the idea that phosphatidylcholine may dissolve β-carotene so that an increase of phosphatidylcholine concentration in the micelles leads to an increase of β-carotene bioaccessibility. When phosphatidylcholine was present together with citrus pectin as emulsifier, the β-carotene bioaccessibility was dependent on the pectin DM whereas the lipid digestion remained again. Since carotenoids and lipids have different structures and polarities, their incorporation may be different, which can be used to engineer targeted (digestive) functionalities in food products. Sugar beet pectin can be chosen as emulsifier if high lipid digestion and reasonable β-carotene bioaccessibility are desired, whereas 4% phosphatidylcholine can be chosen if high β-carotene bioaccessibility and lower lipid digestion are desired. The lowest lipid digestion was found in the emulsions containing pectin with a high DM (2%CP99) or with a low DM (2%CP14) as emulsifier.

Jaar van publicatie:2015

Toegankelijkheid:Closed