Control of lipid digestion and nutraceutical bioaccessibility using starch-based filled hydrogels: Influence of starch and surfactant type

The aim of this study was to prepare starch-based filled hydrogels fortified with a model lipophilic nutraceutical (β-carotene) and determine the influence of starch type (mung bean or rice starch) and surfactant type (whey protein isolate (WPI) or Tween 20 (T20)) on lipid digestibility and β-carotene bioaccessibility. Microstructure, lipid digestion, and β-carotene bioaccessibility were measured as the emulsions and filled hydrogels were passed through a simulated gastrointestinal tract that included oral, gastric, and intestinal phases. The bioaccessibility was defined as the fraction of β-carotene solubilized within the mixed micelle phase after lipid digestion. Non-encapsulated T20-stabilized emulsions had better aggregation stability than WPI-stabilized emulsions under simulated gastrointestinal conditions, which led to a higher β-carotene bioaccessibility. Both Tween 20- and WPI-stabilized emulsions incorporated in starch-based filled hydrogels led to high lipid digestion and β-carotene bioaccessibility. The release behavior of free fatty acids during lipase digestion depended on the type of starch used as a hydrogel matrix, which was attributed to differences in starch structure. The information obtained in this study may be useful for the fortification of starch-based gelled products with lipophilic nutraceuticals.