Influence of dietary lipid physical properties and supramolecular structure on digestibility and nutritional functionality

食物特性是其生物命运的重要决定因素，包括其在胃肠道（GI）中被消化的能力。对于要被吸收的脂质，它们必须首先通过复杂的乳化、水解和增溶过程被增溶（即使其生物可及）。关于脂质结构和物理性质（例如熔化温度、固体脂肪含量、晶体形态、液滴内的分布）如何影响食品中的功能性，有广泛的知识。然而，我们对如何优化这些参数以定制生物利用度和代谢反应的理解还处于相对初级阶段。例如，三酰甘油（TAG）多态性在消化脂解中起什么作用？乳液液滴中结晶度的数量和排列是否会改变包封脂质或组成脂肪酸的释放？TAG结晶度是否可以被设计来改变胶体行为，从而改变胃排空、脂血反应和饱腹感？该提案旨在通过应用基本理化分析、体外消化方法和人体研究工具来解决这些问题。它支持理解食品理化性质和代谢反应之间关系的长期目标。这项研究旨在更好地了解脂质消化的物理基础。它专门旨在确定TAG超分子（与分子）结构和物理性质在GI过程中的作用。将使用调和、剪切和乳化剂-脂质组合来生产含有不同固体脂肪含量和结晶性质（例如，大小、形状、多晶型物、在液滴中的位置）的乳液。将使用静态或动态消化模型将其暴露于代表上消化道的条件下，并取样研究脂解、生物可利用性以及胶体和物理状态的变化。使用回火三肉豆蔻酸甘油酯液滴的实验将解决以下假设：对于相对较低密度的多晶型形式的脂质，界面脂解更快。体外消化方法和生物化学和生物物理技术也将被耦合到研究封装的脂质和脂肪酸溶解的过程中，与TAG的熔化温度和结晶度。最后，由于Glasta微结构可能受到脂质结晶度和物理性质的影响，进而影响胃加工，因此将纳入通过超声进行的胃排空、脂血和饱腹感评级的人体研究，以检查用结晶TAG结构化的乳剂。 总之，关于消化的物理基础存在重大的知识差距，这妨碍了对脂质如何促进代谢功能的充分理解。通过关注TAG物理特性的作用，这项工作将产生新的见解，以支持基于证据的食品和脂质饮食建议的发展。

Food properties are important determinants of their biological fate, including their ability to be digested in the gastrointestinal (GI) tract. For lipids to be absorbed, they must first be solubilized (i.e. made bioaccessible) through complex emulsifying, hydrolyzing and solubilizing processes. There is extensive knowledge about how lipid structure and physical properties (e.g. melting temperature, solid fat content, crystal morphology, distribution within droplets) influence functionality in foods. However, our understanding of how to optimize these parameters to tailor bioavailability and metabolic response is in its relative infancy. For example, what role does triacylglycerol (TAG) polymorphism play in digestive lipolysis? Does the amount and arrangement of crystallinity in an emulsion droplet alter the release of encapsulated lipids or constituent fatty acids? Can TAG crystallinity be engineered to alter colloidal behaviour, and hence gastric emptying, lipemic response and satiety? This proposal aims to address these questions through the application of basic physicochemical analyses, in vitro digestion methods and human research tools. It supports the long-term goal of understanding the relationships between food physicochemical properties and metabolic response. This research targets a better understanding of the physical basis of lipid digestion. It specifically aims to determine the role of TAG supramolecular (vs. molecular) structure and physical properties in GI processes. Emulsions will be produced containing different solid fat contents and crystalline properties (e.g. size, shape, polymorph, location in droplets), using tempering, shear, and emulsifier-lipid combinations. They will be exposed to conditions representative of the upper GI tract using static or dynamic digestion models, with sampling to study lipolysis, bioaccessibility and changes in colloidal and physical state. Experiments with tempered trimyristin droplets will address the hypothesis that interfacial lipolysis is faster for lipids in relatively less dense polymorphic forms. In vitro digestion methods and biochemical and biophysical techniques will also be coupled to investigate the processes of encapsulated lipid and fatty acid solubilization, in relation to TAG melting temperature and crystallinity. Lastly, because digesta microstructure can be influenced by lipid crystallinity and physical properties, and in turn impact gastric processing, human studies of gastric emptying by ultrasound, lipemia, and satiety ratings will be incorporated to examine emulsions structured with crystalline TAG. In summary, there are significant knowledge gaps about the physical basis of digestion that preclude a sufficient understanding of how lipids contribute to metabolic function. By focusing on the role of TAG physical properties, this work will generate novel insights to support the development of evidence-based food products and dietary recommendations for lipids.