Encapsulation of omega-3 fatty acids in bio-based nanoemulsions: physical and chemical characterization

Abstract

[Excerpt] The use of nanotechnology can offer several advantages, not only improving water solubility but also in the increase of bioavailability of lipophilic bioactive compounds. Omega-3 polyunsaturated fatty acids (ω-3 fatty acids) are known for their functional properties such as: improving cardiovascular health, decrease inflammation, increase cognitive function, and positively influence neurological and visual development. However, ω-3 fatty acids are highly susceptible to oxidation, have an intense odour and present low water solubility, which makes their direct application in foods extremely difficult. Nanoencapsulation (through nanoemulsions) may be used to reduce these problems. In this work, lactoferrin (Lf), a protein derived from milk with a wide range of reported biological activities (e.g. antioxidant, antimicrobial and cancer prevention), was used as natural emulsifier for the development of oil-in-water nanoemulsions. Nanoemulsions were produced with a high-pressure homogenizer applied for 5 cycles at 20000 psi. Different Lf concentrations (0.2; 0.6; 1; 2; 3; 4 and 5% (w/w)) were tested. The nanoemulsions’ physical properties were evaluated in terms of size and ζpotential using dynamic light scattering (DLS) and by surface tension using the Ring method. The morphology of nanoemulsions was analysed by transmission electron microscopy (TEM). The physical and chemical stability of these nanoemulsions was assessed during 50 days, at storage temperatures of 4 ºC and 25 ºC, being the chemical stability of nanoemulsions evaluated by antioxidant activity measurements using the DPPH radical scavenging assay. [...]