Hydrolysis of Mixed Lipid Emulsions Containing Medium‐Chain and Long‐Chain Triacylglycerol With Lipoprotein Lipase in Plasma‐like Medium

We explored the effects of plasma‐like conditions on hydrolysis of medium‐chain triglyceride (MCT) and long‐chain triglyceride (LCT) emulsions at different mixing ratios and the effect of the physical method of mixing on lipoprotein lipase hydrolysis of mixed emulsions in vitro. Mixed emulsions with two different mixing ratios, 50% MCTs with 50% LCTs and 70% MCTs with 30% LCTs by weight, were studied. Emulsions containing both MCT and LCT oils blended in the same emulsion particle were compared with mixtures of separate pure MCT emulsion particles and pure LCT particles. MCT hydrolysis was always greater than LCT hydrolysis. In a plasma‐free tris(hydroxymethyl)aminomethane‐albumin buffer at pH 8.5, the physical method of mixing had substantial effects on hydrolysis; blended emulsions of MCTs and LCTs were hydrolyzed better than separate mixes of pure MCT and pure LCT particles, ie, more total free fatty acids were released. In plasma‐free systems, there were no differences in rates of hydrolysis of LCTs or MCTs (as individual triglycerides) between the two different mixing ratios of 50:50 and 70:30. However, the presence of plasma markedly diminished the differences in hydrolysis between blended vs separately mixed emulsions at pH 7.4. Also, in plasma‐like incubation buffer, the rates of hydrolysis of MCTs and LCTs in emulsions with 50:50 or 70:30 MCT to LCT ratios reflected the respective amounts of MCT and LCTs in the emulsions. These data suggest that there are no significant differences in hydrolysis between blended and separately mixed MCT and LCT emulsions in plasma at pH 7.4, and that the rate of release of total free fatty acids during emulsion hydrolysis is largely dependent on the initial amount of MCT in the mixture. ( Journal of Parenteral and Enteral Nutrition 18 :112–118, 1994)