Evaluation of oral bioaccessibility of aged citrus peel extract encapsulated in different lipid based systems: a comparison study using different in vitro digestion models.

The oral delivery efficiency of aged citrus peel extract containing polymethoxyflavones and 5-demethylated polymethoxyflavones (PMFs) in three different systems including pure oil phase, Tween 80 stabilized nanoemulsion and milled cellulose particles stabilized Pickering emulsion, was investigated using two typical in vitro digestion models. The digestion profiles and release of PMFs in these emulsions and bulk oil in the human upper gastrointestinal (GI) tract were evaluated using pH-stat lipolysis model and TNO's gastrointestinal model (TIM-1). Compared to bulk oil sample, the bioaccessibilities of PMFs in nanoemulsion and Pickering emulsion were both increased by around 14 folds when pH-stat lipolysis model was used. However, the results from TIM-1 system indicated that the bioaccessibilities of PMFs in nanoemulsion and Pickering emulsion were around 2 and 4 times of that in bulk oil, respectively. The results from this work would provide valuable information for the rational design and evaluation of lipid based delivery systems for lipophilic bioactive compounds.