The effect of pectin on in vitro β-carotene bioaccessibility and lipid digestion in low fat emulsions

Abstract

11Soluble fibers, like pectin, are known to influence the physicochemical processes during the digestion 12 of dietary fat and may therefore affect the absorption of lipophilic micronutrients such as 13 carotenoids. The objective of the current work was to investigate whether the pectin concentration 14 and degree of methyl-esterification (DM) influence the bioaccessibility of carotenoids loaded in the 15 oil phase of oil-in-water emulsions. The in vitro β-carotene bioaccessibility was determined for 16 different oil-in-water emulsions in which 1 or 2% citrus pectin with a DM of 99%, 66% and 14% was 17 present. Results show that pectin concentration and DM influence the initial emulsion properties. 18The most stable emulsions with the smallest oil droplets (D(v,0.9) of 15-16 µm) were obtained when 19 medium or high methyl-esterified pectin was present in a 2% concentration while gel-like pectin 20 structures (D(v,0.9) of 114 µm), entrapping oil droplets, were observed in case low methyl-esterified 21 pectin was present in the aqueous emulsion phase. During in vitro stomach digestion, these gel-like 22 structures, entrapping β-carotene loaded oil droplets, significantly enlarged (D(v,0.9) of 738 µm), 23 2 whereas the emulsion structure could be preserved when medium or high methyl-esterified pectin 24 was present. Initial emulsion viscosity differences, due to pectin concentration and especially due to 25 pectin DM, largely disappeared during in vitro digestion, but were still significant after the stomach 26 digestion phase. The observed differences in emulsion structure before and during in vitro digestion 27 only resulted in a significant difference between emulsions containing low methyl-esterified pectin 28 (β-carotene bioaccessibility of 33-37%) and medium/high methyl-esterified pectin (β-carotene 29 bioaccessibility of 56-62%). 30

In vitro β‐Carotene Bioaccessibility and Lipid Digestion in Emulsions: Influence of Pectin Type and Degree of Methyl‐Esterification

“…It seems that the β‐carotene bioaccessibility increased if the lipid digestion increased, although the magnitude to which the increase occurred was different. Both results were also found by Verrijssen and others (). Therefore, the following hypothesis can be stated.…”

“…First, smaller oil droplets were found in the CP57 emulsion (median ( = D[v; 0.5]) of 1.8 μm and D[v; 0.9] of 4.2 μm) compared to oil droplets in the CP30 emulsion (median of 5.5 μm and D[v; 0.9] of 17.4 μm; Figure A and confirmed by microscopy [results not shown]), so it seems that CP57 had a better emulsifying capacity compared to CP30. Probably in CP57, the block‐wise patterns of hydrophilic and hydrophobic groups of the GalA‐molecules (at pH 6) emulsified better compared to the more hydrophilic molecules in CP30 (Fraeye and others ; Verrijssen and others ). It can be concluded that the DM in the CP emulsions is important for the oil droplet size distribution.…”

“…The pectin functional properties differ depending on their structural characteristics (Christiaens and others ,b). For example, the pectin emulsifying capacity has been hypothesized to depend on pectin DM (Verrijssen and others ), pectin DA (Leroux and others ), or attached proteins (Siew and others ).…”

In Vitro Bioaccessibility of Colored Carotenoids in Tomato Derivatives as Affected by Ripeness Stage and the Addition of Different Types of Oil

“…In this regard, the higher DM of pectin in unripe tomatoes could hinder the incorporation of carotenoids into micelles resulting in lower bioaccessibility. Similar results were found by Verrijssen, Verkempinck, Christiaens, Van Loey, and Hendrickx (2015) who reported an increase of the incorporation of β-carotene into the micelles by decreasing the pectin DM of the emulsions. In addition, the depolymerization process could also facilitate the disruption of cell walls during digestion, allowing the release of carotenoids from tomato matrix and promoting their micellar solubilization (Ornelas-Paz et al, 2008).…”

Improving the In Vitro Bioaccessibility of β-Carotene Using Pectin Added Nanoemulsions

“…Emulsion-based delivery systems can be produced using various emulsification processes and they have been widely used to protect bioactive compounds such as carotenoids from degradation, ameliorate its dispersion in an aqueous media, and increase its bioaccessibility [10][11][12][13][14][15][16]. However, in the last years, oil droplet reduction in the range of 20-500 nm [17] showed several advantages over conventional emulsions.…”