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

食物特性是它们生物命运的重要决定因素，包括它们在胃肠道(GI)中的消化能力。对于要被吸收的脂类，首先必须通过复杂的乳化、水解和增溶过程将其溶解(即使其具有生物可获得性)。关于脂类结构和物理性质(例如，熔化温度、固体脂肪含量、晶体形态、液滴中的分布)如何影响食品的功能性，有广泛的知识。然而，我们对如何优化这些参数以适应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)基因多态性在消化性脂肪分解中起什么作用？乳状液滴中结晶度的数量和排列是否会改变被包裹的脂类或组成脂肪酸的释放？TAG结晶度能否被改造来改变胶体行为，从而改变胃排空、血脂反应和饱腹感？这项建议旨在通过应用基本的物理化学分析、体外消化方法和人类研究工具来解决这些问题。它支持理解食物的物理化学性质和代谢反应之间的关系的长期目标。这项研究旨在更好地了解脂肪消化的物理基础。它的具体目的是确定标签超分子结构和物理性质在GI过程中的作用。将使用回火、剪切和乳化剂-脂肪组合来生产含有不同固体脂肪含量和结晶特性(例如，大小、形状、多晶型、在液滴中的位置)的乳液。他们将使用静态或动态消化模型暴露在具有上消化道特征的条件下，取样研究脂肪分解、生物可及性以及胶体和物理状态的变化。对于密度相对较低的多晶型的脂类，使用调质的曲霉素液滴进行的实验将解决这样一种假设，即界面脂解速度更快。体外消化方法以及生化和生物物理技术也将结合起来研究包埋脂肪和脂肪酸的溶解过程，以及与标签熔化温度和结晶度的关系。最后，由于消化液的微结构可能会受到脂肪结晶度和物理性质的影响，进而影响胃的加工过程，因此人类对超声波胃排空、血脂和饱腹感评级的研究将被纳入检查具有结晶标签结构的乳剂。总而言之，关于消化的物理基础有很大的知识空白，这排除了对脂质如何促进代谢功能的充分了解。通过关注标签物理特性的作用，这项工作将产生新的见解，以支持基于证据的食品产品和血脂饮食建议的开发。

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.