|Ph.D Student||Pascoviche Dafna|
|Subject||Characterization of Multifunctional Colloid-Stabilized|
Emulsions and Evaluating their Potential Digestive
|Department||Department of Biotechnology and Food Engineering||Supervisor||Professor Uri Lesmes|
|Full Thesis text|
Recently, efforts were made to develop food grade emulsion-based systems tackling modern morbidity as they are natural, efficient and cost effective. Particularly, there is an effort to tailor such multifunctional systems that can offer the consumer a multitude of benefits, beyond a single bioactive component. This work was aimed to explore the fabrication of colloid-stabilized multifunctional-emulsions and to study the potential digestive fate of its emulsifiers and lipid core.
First, we describe the formulation of Extra Virgin Olive Oil (EVOO) emulsions stabilized by proteinaceous particles or by a novel hydrophobically modified inulin (HMI). The physical characteristics were examined and these systems were further analyzed under conditions mimicking adult human digestive tract. It was found that the processing of lactoferrin (LF) into protein-polysaccharide nano-particles (NPs) formed via electrostatic interactions, improved emulsion physical stability and altered its digestive fate. Interestingly, lactoferrin-carrageenan NPs yield emulsions with a higher extent of intestinal lipolysis (10% increase) while lactoferrin-alginate NPs reduce it (14% reduction) compared to LF, LF-NPs and b-lactoglobulin stabilized emulsions. The use of HMI is shown to yield emulsions with high stability to pH (8.0-2.0), ionic strength (0-40 mM CaCl2), semi-dynamic in-vitro gastric digestion (0-2 h) as well as modulated simulated intestinal lipolysis (0-2 h).
Furthermore, this work extends previous studies utilizing LF to stabilize emulsions of three bioactive lipids: EVOO composed of mainly 18:1 fatty acids (FA), Hemp Seed Oil (HSO) composed primarily of 18:2 FA and Pomegranate Seed Oil (PSO) rich in 18:3 FA. It demonstrated the effect of lipid composition on droplet interfacial properties and consequently emulsions properties, as well as susceptibility to intestinal lipolysis. Specifically, result indicate that the altering of droplet FA composition using glyceryl trioleate (TOLN) doping at varying concentrations (1%, 2%, 5% and 10% [w/w]) tempers emulsion stability, droplet size and size distribution. Also, TOLN markedly accelerated and enhanced the lipolysis of PSO containing emulsions. Fatty acid methyl esters (FAME) profiling of intestinal digesta indicated the preferential liberation of saturated, then monounsaturated and lastly polyunsaturated FA from the various droplets.
Additionally, the contribution of gastric lipolysis is known to be imperative to human digestion. Yet, it is difficult to mimic due to challenges in its production as well as different biochemical properties and performances of common replacements. Therefore, emulsion gastro-duodenal digestion was applied under various conditions in the presence of a novel recombinant human gastric lipase (rHGL) comparing to a common replacement. Insights from this part demonstrate the importance of gastric lipolysis to emulsion digestion as droplets size and overall spatial organization differ in the absence of gastric lipase. Conclusions also enhance the importance of incorporating gastric lipase when applying in vitro digestion on lipid-containing formulations.
Overall, this study demonstrated the ability of multifunctional emulsions to act as modifiers of digestion patterns, with insights suggesting a possible control on satiation and satiety. The new procedures generated herein for the execution of in vitro digestion protocols and for the analyses of such formulations are valuable and already being used in studies further exploring emulsion digestive fate.