Influence of emulsifier type and encapsulating agent on the in vitro digestion of fish oil-loaded microcapsules produced by spray-drying

Abstract

The influence of the emulsifier type and the encapsulating agent on the bioaccessibility of microencapsulated fish oil was investigated. Fish oil-loaded microcapsules were produced by spray-drying using carbohydrate-based encapsulating agents (glucose syrup or maltodextrin). Whey protein concentrate hydrolysate (WPCH) or Tween 20 (TW20) were used as the emulsifiers. The microcapsules were subjected to a three-phase in vitro digestion (oral, gastric, and intestinal phase) and the changes in the physicochemical properties of the samples were monitored throughout the simulated gastrointestinal tract (oil droplet size, ζ-potential, and microstructure). The lipolysis rate and extent were evaluated at the intestinal digestion phase. Contrary to the encapsulating agent, the emulsifier used in the infeed emulsion formulation significantly influenced lipid digestion. WPCHbased interfacial layer prevented oil droplets coalescence during and after processing more efficiently than TW20, which resulted in an increased specific surface area for lipases to adsorb and thus a higher bioaccessibility of the microencapsulated oil.