Antioxidant benefits of Ecklonia radiata algae phenolic extracts in food grade omega-3 delivery systems

Seaweed phenolics are an attractive, sustainable source of natural phenolic antioxidants, and have potential for stabilising complex food and feed systems. In the present study, three seaweeds collected along the Victoria coastline of Australia were extracted and screened for phenolic content and antioxidant activity. A 70/30 ethanol/water extract of Ecklonia radiata was selected and major phenolics were characterised using LC-ESI-QTOF-MS/MS, with eckol-type phlorotannins being the identified as the most abundant in this extract. This Ecklonia radiata extract was able to oxidatively stabilise tuna oil-in-water emulsion at low concentrations but showed some pro-oxidant effects in at higher concentrations in both emulsions and microcapsules omega-3 delivery systems. Ecklonia radiata phenolics are useful for oxidative stabilisation but results indicate that phenolic levels need to be specifically tailored for each application, particularly for complex food delivery systems.