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

• β-Carotene-loaded oil droplets were encapsulated in starch-based hydrogels.
• The impact of methylcellulose on gastrointestinal fate of droplets was determined.
• Methylcellulose did not alter starch hydrogel rheology, but delayed lipid digestion.
• Carotenoid bioaccessibility was reduced at higher methylcellulose levels.

There is considerable interest in controlling the gastrointestinal fate of nutraceuticals to improve their efficacy. In this study, the influence of methylcellulose (an indigestible polysaccharide) on lipid digestion and β-carotene bioaccessibility was determined. The carotenoids were encapsulated within lipid droplets that were then loaded into rice starch hydrogels containing different methylcellulose levels. Incorporation of 0 to 0.2% of methylcellulose had little impact on the dynamic shear rheology of the starch hydrogels, which may be important for formulating functional foods with desirable textural attributes. The microstructure, lipid digestion, and β-carotene bioaccessibility of the filled hydrogels were measured as the samples were passed through simulated oral, gastric, and small intestinal phases. The lipid digestion rate and carotenoid bioaccessibility decreased with increasing methylcellulose. This effect was attributed to the ability of the methylcellulose to inhibit molecular diffusion, promote droplet flocculation, or bind gastrointestinal components thereby inhibiting triacylglycerol hydrolysis at the lipid droplet surfaces. This information may be useful for rationally designing functional foods with improved nutritional benefits.

Confocal micrographs showing microstructural changes during passage through simulated oral, gastric, and intestinal phases; (A) emulsions; (B) filled starch hydrogels without methylcellulose, (C) filled starch hydrogels containing 0.05% methylcellulose; and (D) filled starch hydrogels containing 0.2% methylcellulose.Figure optionsDownload as PowerPoint slide