The oxidative stability of omega-3 oil-in-water nanoemulsion systems suitable for functional food enrichment: A systematic review of the literature

There is growing demand for functional food products enriched with long chain omega-3 polyunsaturated fatty acids (LC omega 3PUFA). Nanoemulsions, systems with extremely small droplet sizes have been shown to increase LC omega 3PUFA bioavailability. However, nanoemulsion creation and processing methods may impact on the oxidative stability of these systems. The present systematic review collates information from studies that evaluated the oxidative stability of LC omega 3PUFA nanoemulsions suitable for use in functional foods. The systematic search identified seventeen articles published during the last 10years. Researchers used a range of surfactants and antioxidants to create systems which were evaluated from 7 to 100days of storage.Nanoemulsions were created using synthetic and natural emulsifiers, with natural sources offering equivalent or increased oxidative stability compared to synthetic sources, which is useful as consumers are demanding natural, cleaner label food products. Equivalent vegetarian sources of LC omega 3PUFA found in fish oils such as algal oils are promising as they provide direct sources without the need for conversion in the human metabolic pathway. Quillaja saponin is a promising natural emulsifier that can produce nanoemulsion systems with equivalent/increased oxidative stability in comparison to other emulsifiers. Further studies to evaluate the oxidative stability of quillaja saponin nanoemulsions combined with algal sources of LC omega 3PUFA are warranted.