The effect of pectin concentration and degree of methyl-esterification on the in vitro bioaccessibility of β-carotene-enriched emulsions

Abstract

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

Influence of methylcellulose on attributes of β-carotene fortified starch-based filled hydrogels: Optical, rheological, structural, digestibility, and bioaccessibility properties

“…In their study, anionic dietary fibers (pectin) were used, which may have interacted with cationic calcium ions and formed a gel-network that inhibited lipase diffusion or prevented calcium soaps of FFAs being formed. Other studies have suggested that dietary fibers may impact lipid digestion by binding to various components in the GIT, such as calcium ions, bile salts, free fatty acids, and lipase (Palafox-Carlos, Ayala-Zavala, & Gonzalez-Aguilar, 2011;Verrijssen et al, 2014;Qiu, Zhao, Decker, & McClements, 2015). A differential scanning calorimetry study of cellulose ester-bile salt mixtures showed that the bile salts affected the thermal gelation of the cellulose derivatives, which suggested that there was some kind of binding interaction (Torcello-Gόmez & Foster, 2014).…”

“…Thus, the retardation of lipid digestion observed at high methylcellulose levels may have been partially due to binding of bile salts. Alternatively, it may have been due to the ability of the methylcellulose to increase the viscosity of the aqueous phase around the lipid droplets, thereby slowing down the diffusion of reactants, catalysts, and products involved in the lipid digestion process (Palafox-Carlos et al, 2011;Tokle et al, 2012;Verrijssen et al, 2014).…”

“…Many of these nutraceuticals cannot simply be introduced into functional foods in their pure form because of physicochemical constraints, such as limited solubility, chemical instability, and poor bioavailability (Liang, Shoemaker, Yang, Zhong, & Huang, 2013;McClements, 2013;Reboul, 2013;Tang & Zhong-Gui, 2007). These challenges can often be overcome using food-grade colloidal delivery systems, such as emulsions, nanoemulsions, microemulsions, solid lipid nanoparticles, and filled hydrogels (Mun, Kim, Shin, & McClements, 2015;Nik, Langmaid, & Wright, 2012;Tokle, Lesmes, Decker, & McClements, 2012;Verrijssen et al, 2014;Zhang et al, 2015). Lipophilic nutraceuticals can be encapsulated within lipid droplets that can readily be dispersed in water, that can protect the bioactives from degradation, and that are digested in the gastrointestinal tract (GIT) to form mixed micelles that enhance bioaccessibility (McClements, 2013).…”

Functional properties of citric acid extracted mango peel pectin as related to its chemical structure

“…Measurements were performed at 25 C in a stress-controlled rheometer (MCR 501, Anton Paar, Graz, Austria) using a concentric cylinder geometry (double-wall couette) (Verrijssen et al, 2014). In order to avoid the effect of loading history on the samples, a constant shear rate of 100 s À1 was applied for 60 s, followed by a rest-period of 300 s (shear rate of 0 s À1 ).…”

Designing hydrogel particles for controlled or targeted release of lipophilic bioactive agents in the gastrointestinal tract

“…The integrity of calcium pectinate beads can be reinforced by formation of polyelectrolyte coatings around them, e.g., by electrostatic deposition of cationic biopolymers (such as chitosan) onto the anionic beads[43]. The charge characteristic of pectin can be selected to control lipid digestion and bioactive release, e.g., it has been shown that decreasing DE reduced lipid digestion and bioactive bioavailability[44][45][46].…”