Typically, omega-3 is encapsulated in a nanoemulsion of synthetic surfactants to make the fatty acid more water-soluble, stable, and easily absorbed.
The problem is that, if the manufacturer wishes to market their product as something GMO-free and have low allergenicity, the typical nanoemulsion surfactant isn’t the best option. Researchers from the University of Massachusetts, Amherst, looked at the potential natural emulsifiers—phospholipids, proteins, and polysaccharides—to encapsulate an omega-3 nanoemulsion.
Their study, published in the journal Food Chemistry, looked at sunflower phospholipids “which are not [common sources] of allergens, and which are not obtained from a genetically modified organism.”
Emulsifying fish oil
The goal was to see if “stable omega-3 nanoemulsions containing small oil droplets could be fabricated using microfluidizationn and sunflower phospholids,” the researchers wrote.
Using four different natural phospholipid surfactants derived from sunflower oil, with differing levels of phosphatidylcholine, donated by New York-based Perimondo (Sunlipon 50, 65, 75, and 90).
An aqueous emulsifier solution was prepared by dispersing the phospholipids in the aqueous phase made with a sodium phosphate buffer solution, stirring overnight at room temperature. Coarse emulsions were then prepared by blending organic fish oil phase (Ropufa 30 n-3 from Swiss company DSM Nutritional Products) with the aqueous phase using a high-speed blender for two minutes.
The coarse emulsions were then passed through a microfluidizer for three cycles at 12,000 psi to produce the nanoemulsions.
Testing the nanoemulsions
Five variables were tested to rate the nanoemulsion’s success: the phospholipid composition, surfactant-to-oil ratio, oil presence, effect of pH on emulsion stability, and effect of salt on emulsion stability.
The samples were analyzed using several techniques, including particle size analysis, zeta potential analysis (the electrical charge on the droplets), visual observation, and optical microscopy.
Analyzing all variables with the different techniques, the researchers found that “omega-3 enriched nanonemulsions can be produced by microfluidization using certain kinds of natural sunflower phospholipids.”
The higher the overall phospholipid concentration in an emulsion, the smaller the droplet size. The researchers wrote that “there appeared to be no simple correlation between the phosphatidylcholine content of the phospholipid ingredients, and their ability to form small droplets.”
Under conditions where the droplets had low net charges or where the aqueous phase had a high ionic strength, the emulsions were susceptible to aggregation. “These results suggest that sunflower phospholipids can be used as natural emulsifiers to form omega-3 nanoemulsion-based delivery systems suitable for application in certain types of foods and beverages,” the researchers wrote. “However, it is important to ensure that the pH and ionic strength of a particular product do not promote droplet aggregation by reducing electrostatic repulsion.”
The researchers recommended future studies in the chemical stability of these systems.
Commenting independently on the study, Gerard Bannenberg, Director of Compliance & Scientific Outreach for the Global Organization for EPA and DHA Omega-3 (GOED), told us that nanoemulsions of omega-3 long-chain polyunsaturated fatty acids have been reported with various natural emulsifying or encapsulating agents: nanoemulsions stabilized with quillaja saponins; nanodroplets encapsulated in chitosan; nanoemulsions prepared from omega-3 PUFA-containing phosphatidylcholine phospholipids themselves stabilized with betulinic acid; salmon oil nanoemulsions stabilized with salmon-, soya-, and rapeseed phosphatidylcholine; and nanosized phosphatidylcholine-omega-3 ethyl ester-magnetoliposomes.
"The studied sunflower phospholipid extracts are mixtures of a number of lipids in which phosphatidylcholine is the major component," he said. "The other lipid species do contribute to achieving stable nanoemulsions of fish oil. It is possible to determine if phospholipid extracts from other sources may also be suitable for various final applications."
Source: Food Chemistry
First published online, doi:10.1016/j.foodchem.2016.02.080
“Encapsulation of ω-3 fatty acids in nanoemulsion-based delivery systems fabricated from natural emulsifiers: Sunflower phospholipids”
Authors: J. Komaiko, et al