Nonomura Yoshimune, Nakayama Keisuke, Aoki Yuki, Fujimori Atsuhiro
Department of Chemistry and Chemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan.
J Colloid Interface Sci. 2009 Nov 1;339(1):222-9. doi: 10.1016/j.jcis.2009.07.030. Epub 2009 Jul 18.
Dietary lipids are solubilized in bile acid micelles in the small intestine. In the present study, we investigate the phase behavior of bile acid/model rapeseed oil (or model beef tallow)/water systems to predict interfacial phenomena during consumption of a variety of foods. The structures of molecular assemblies are identified based on polarizing microscope images, wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). The results of in vitro tests suggest that an increase in the intake of model rapeseed oil causes the formation of multi-lamellar vesicles and lamellar liquid crystals. The molecules in the lamellar liquid crystal are formed highly ordered layer structure with the spacing of 8.8nm along the c-axis, while monoclinic packed structure is constructed as two-dimensional structure in ab-plane due to bulky molecular structures of bile acid and unsaturated fatty acid. When the model beef tallow composition in the model system is more than several wt.%, stearic acid crystals are extracted. Moreover, bicarbonate ions are important ingredients to solubilize >10wt.% of the model lipids. These phase transitions might be induced by the addition of dietary lipids in vivo during the consumption of oil or meat. Our findings are significant for understanding the lipid absorption process in the small intestine, and for developing medical and healthcare products.
膳食脂质在小肠中被溶解于胆汁酸微团中。在本研究中，我们研究胆汁酸/模型菜籽油（或模型牛油）/水体系的相行为，以预测食用各种食物期间的界面现象。基于偏光显微镜图像、广角X射线衍射（WAXD）和小角X射线散射（SAXS）来确定分子聚集体的结构。体外试验结果表明，模型菜籽油摄入量的增加会导致多层囊泡和层状液晶的形成。层状液晶中的分子形成高度有序的层状结构，沿c轴间距为8.8nm，而由于胆汁酸和不饱和脂肪酸的庞大分子结构，单斜堆积结构在ab平面中构建为二维结构。当模型体系中的模型牛油成分超过几个重量百分比时，会析出硬脂酸晶体。此外，碳酸氢根离子是溶解超过10重量百分比的模型脂质的重要成分。这些相变可能是在食用油或肉类期间体内添加膳食脂质所诱导的。我们的研究结果对于理解小肠中的脂质吸收过程以及开发医疗和保健产品具有重要意义。
