In the present study, we use a model gastro-intestinal system to study the influence of different food-grade surface-active molecules (Sn-2 monopalmitin, beta-lactoglobulin, or lysophosphatodylcholine) on lipase activity. The interfacial activity of lipase and surfactants are assessed with the pendant drop technique, a commonly used tensiometry instrument. A mathematical model is adopted which enables quantitative determination of the composition of the water-oil interface as a function of bulk surfactant concentration in the water-oil mixtures. Our results show a decrease in gastric lipolysis when interfacially active molecules are incorporated into a food matrix. However, only the Sn-2 monopalmitin caused a systematic decrease in triglyceride hydrolysis throughout the gastro-intestinal tract. This effect is most likely due to exclusion of both lipase and triglyceride from the water-oil interface together with a probable saturation of the solubilization capacity of bile with monoglycerides. Addition of beta-lactoglobulin or lysophopholipids increased the hydrolysis of fat after the gastric phase. These results can be attributed to an increasing interfacial area with lipase and substrate present at the interface. Otherwise, beta-lactoglobulin, or lysophopholipids reduced fat hydrolysis in the stomach. From the mathematical modeling of the interface composition, we can conclude that Sn-2 monopalmitin can desorb lipase from the interface, which, together with exclusion of substrate from the interface, explains the gradually decreased triglyceride hydrolysis that occurs during the digestion. Our results provide a biophysics approach on lipolysis that can bring new insights into the problem of fat uptake.

中文翻译：

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表面活性剂对模型胃肠系统中脂肪酶脂肪消化的影响。

在本研究中，我们使用胃肠系统模型来研究不同食品级表面活性分子（Sn-2 单棕榈酸、β-乳球蛋白或溶血磷脂酰胆碱）对脂肪酶活性的影响。脂肪酶和表面活性剂的界面活性通过悬滴技术（一种常用的张力测定仪器）进行评估。采用的数学模型能够定量确定水-油界面的组成作为水-油混合物中本体表面活性剂浓度的函数。我们的结果表明，当界面活性分子掺入食物基质中时，胃脂肪分解会减少。然而，只有 Sn-2 单棕榈酸甘油酯引起整个胃肠道甘油三酯水解的系统性降低。这种效应很可能是由于脂肪酶和甘油三酯被排除在水-油界面之外，以及胆汁与甘油单酯的溶解能力可能饱和。添加β-乳球蛋白或溶血磷脂增加了胃期后脂肪的水解。这些结果可归因于界面处存在脂肪酶和底物的界面面积增加。另外，β-乳球蛋白或溶血磷脂可以减少胃中的脂肪水解。从界面组成的数学模型中，我们可以得出结论，Sn-2 单棕榈酸可以从界面上解吸脂肪酶，这与界面上底物的排除一起解释了消化过程中发生的甘油三酯水解逐渐减少。我们的研究结果提供了一种关于脂肪分解的生物物理学方法，可以为脂肪摄取问题带来新的见解。