CHARACTERIZATION OF EMULSIONS AND LIPOLYSIS OF DIETARY LIPIDS IN THE HUMAN STOMACH

Characterization of emulsions and lipolysis of dietary lipids in the h uman stomach. Am. J. Physiol. 266 (Gastrointest. Liver Physiol. 29): G 372-G381, 1994. - Fasting subjects were intragastrically intubated and received a coarsely emulsified test meal. Gastric aspirates were coll ected after 1, 2, 3, and 4 h. During digestion in the stomach, unemuls ified lipids (greater than or equal to 100 mu m) represented a minor f raction. A significant amount of the large 70- to 100-mu m lipid dropl ets disappeared, and fine 1- to 10-mu m droplets were generated. The m edian lipid droplet diameter significantly decreased (21.9 vs. 52.9 mu m) after 1 h and kept intermediate values for longer periods of time. The emulsion surface area was 100-120 m(2)/l and was basically provid ed by 1- to 100-mu m droplets. Lipolysis catalyzed by gastric lipase p rimarily occurred within the first hour of digestion (11.9%). Smaller droplets were enriched in triglyceride lipolytic products. The free fa tty acid concentrations were in the range of 5.6-8.2 mill over 1-4 h. The present finding demonstrates for the first time that in the human stomach most dietary lipids are present in the form of emulsified drop lets, in the range of 20-40 mu m, and that gastric lipolysis can help to increase emulsification in the stomach.