Structured Emulsion Design for Saturated Fat Reduction and Animal Fat Replacement

Candidate: Natalia Mello
Supervisor: Dr. Dérick Rousseau

Abstract:

The shift toward plant-based diets and/or the need to reduce saturated fat intake have driven efforts to develop food products aligned with health and ethical values. Structured emulsions offer a promising strategy to meet these goals. This thesis comprises three studies that investigated the structure–function relationship in both water-in-oil (W/O) and oil-in-water (O/W) emulsions. The first study investigates W/O high internal phase emulsion stabilized with polyglycerol polyricinoleate (PGPR) and structured by small amount of fully hydrogenated soybean oil. The incorporation of crystallized lipids into the continuous phase enhanced emulsion rigidity and suppressed visible phase separation. However, increased solid fat also led to greater droplet coalescence over time, highlighting a trade-off between structural reinforcement and microstructural stability. This study provides valuable insights for the food industry in the development of low-saturated-fat mimetics. The second study focuses on soy protein-stabilized palm oil-in-water emulsions (O/W) containing glycerol monostearate (GMS) and oat fibre. GMS improved emulsification efficiency and enhanced interfacial structuring through partial protein displacement and potential crystallization at the interface. Oat fibre increased the firmness of the emulsions and improved their resistance to heat-induced breakdown. While GMS-containing emulsions destabilized upon heating, the addition of fibre helped retain structural integrity. This work is significant as it provides insights into how interfacial and bulk-phase structuring agents can be combined to develop heat-resistant, firm emulsions suitable for animal fat replacement. Finally, the last study examines shear-induced partial coalescence in palm oil-in-water emulsions (O/W) stabilized by soy protein, polysorbate 80, and GMS. Polysorbate 80 displaced interfacial protein and promoted droplet aggregation under shear, leading to increased viscosity and instability. The addition of GMS counteracted this effect by likely forming a stabilizing crystalline shell around droplets, thereby improving shear resistance and preventing large aggregate formation. This study is important for understanding how surfactant-soy protein interactions influence emulsion behavior under mechanical stress, knowledge that is essential for developing shear sensitive emulsions used in whipped or aerated dairy alternatives products.