Effects of recombinant human gastric lipase and pancreatin during in vitro pediatric gastro-intestinal digestion.

The aim of the study was to implement a gastric digestion step using recombinant human gastric lipase (rHGL) in an in vitro pediatric gastro-intestinal digestion model to achieve a physiologically relevant gastric contribution to total gastro-intestinal lipid digestion. A commercial infant formula (NAN Comfort stage 1 (NAN1)) with 3.4% lipid and an in-lab prepared oil-in-water emulsion, emulsified with soy phosphatidylcholine (SPCemul), with 3.5% lipid (oil-blend containing Akonino NS, MEG-3 and ARASCO oils) were subjected to in vitro gastro-intestinal digestion. To achieve a physiologically relevant level of gastric digestion, 50 min of in vitro gastric digestion, using either 0, 3.75 or 7.5 TBU mL rHGL, was followed by 90 min of in vitro intestinal digestion, using either 0 or 26.5 TBU mL pancreatic triglyceride lipase (PTL) from porcine pancreatin. The digestion of the substrates was assessed using titration-based quantification supported by HPLC-ELSD analysis. In vitro gastric digestion of NAN1 and SPCemul with either 3.75 or 7.5 TBU mL rHGL contributed with 10-27% of the total gastro-intestinal digestion, corresponding to the reported contribution in human infants. At the end of the gastro-intestinal digestion (t = 140 min), the combined lipolytic effect of rHGL and PTL was additive during digestion of SPCemul, but not for the digestion of NAN1, as all lipase activity combinations resulted in a similar degree of NAN1 digestion. The effect of gastric digestion with rHGL on total digestion therefore appeared to be substrate dependent. To conclude, a gastric digestion step using rHGL resulting in physiologically relevant gastric contribution to the observed gastro-intestinal digestion was successfully implemented into an in vitro pediatric gastro-intestinal digestion model.