Assessment of dynamic bioaccessibility of curcumin encapsulated in milled starch particles stabilized Pickering emulsions using TNO’s gastrointestinal model

Pickering emulsions stabilized by milled starch particles have been developed as a novel food-grade formulation to enhance the bioaccessibility of poorly-soluble bioactive compound (i.e., curcumin) through controlling the digestion of lipids in the human gastrointestinal (GI) tract. The dynamic bioaccessibilities of curcumin with and without encapsulation in Pickering emulsion were evaluated using dynamic TNO’s gastrointestinal (TIM-1) model. For comparison, their digestion profiles were also studied using in vitro pH-stat lipolysis model. With the combination of two in vitro models, the mechanism of milled starch particles stabilized Pickering emulsions on the bioaccessibility of curcumin was fully revealed. There are large differences between the bioaccessibility values of curcumin samples obtained by these two models. Simulated small intestinal lipolysis in a pH-stat model revealed that the bioaccessibility of curcumin encapsulated in Pickering emulsion was 27.6%, which was larger than 22.1% for free curcumin suspended in bulk oil phase. The bioaccessbility of curcumin was 50.7% in emulsion system and 7.8% in bulk oil when using TIM-1 model, which simulated the digestion conditions of entire human GI tract. The digestion mechanism of milled starch particles stabilized Pickering emulsions in the upper GI tract was well-elucidated by the TIM-1 model. The gradual release and improved dissolution profile of milled starch particles stabilized Pickering emulsions highlighted their potential as delivery systems for lipophilic bioactive compounds.