Development of an in vitro mechanical gastric system (IMGS) with realistic peristalsis to assess lipid digestibility

A new in vitro mechanical gastric system (IMGS) was fabricated which incorporates: a J-shaped stomach, a mechanical system with realistic peristaltic frequency and force magnitude, and a reproduction of the gastric pH curve. To evaluate the impact of a more realistic gastric peristalsis on the intestinal lipolysis of protein-stabilized O/W emulsions, the emulsions were subjected to two different in vitro digestion methodologies: (i) gastric digestion in the IMGS and intestinal digestion in a stirred beaker (SB), and (ii) gastric and intestinal digestion assays carried out in SBs. At the end of the intestinal digestion, the total amount of free fatty acids released was significantly higher for the first methodology (IMGS-SB) in comparison with the second one (27.5% vs. 23.0%), probably due to the higher physical instability induced by the IMGS in the gastric contents. These results reaffirm that O/W emulsion stability plays a crucial role in controlling the final extent of lipolysis of this kind of food-grade emulsions.