Abstract
Development of low-fat oil-in-water emulsions has several challenges as oil plays important role for stability, textural, rheological, and sensory properties of emulsions. “Fat mimetics” can help to gain acceptable rheology of low-fat emulsions. The physical and oxidative stability of emulsions during storage is mainly influenced by the structure and the content of emulsifier adsorbed on the water–oil interface and the content and composition of oil. A good emulsifier possesses a balance between polar and nonpolar groups for an optimal surface activity and water solubility. The capacity of emulsifiers to modify the behavior of flavor release is also important for the overall product perception by consumers. Due to high percentage of aqueous phase, without the addition of a proper emulsifier, low-fat emulsions are thermodynamically unstable systems, which tend to quickly break down and separate into several phases due to the following instability mechanisms: gravitational separation, flocculation, coalescence, and Ostwald ripening. When incorporating healthy oils rich in long-chain highly unsaturated fatty acids (e.g., fish oil), oxidative stabilization of the emulsion is very important and challenging. The lipid oxidation may be promoted both by formulation of emulsions and during storage. Several factors affect oxidative lipid stability in emulsions including interfacial area, droplet size, fat content, composition of aqueous phase, presence of free fatty acids, pH, and antioxidants. Since the emulsifier is located at the interphase between oil and water, it is very important that the emulsifier protects oil from contact with water-soluble prooxidants. Effect of antioxidants depends on prooxidants and composition of emulsion and should be considered during selection.