Compositional information useful for authentication of krill oil and the detection of adulterants

Abstract Nuclear magnetic resonance (NMR) spectroscopy and chromatography, particularly thin layer chromatography with flame ionisation detector (TLC-FID), were used to investigate fish oil adulteration of krill oil with ethyl esters and triacylglycerol. Natural krill oil has higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in phospholipid than in triacylglycerol and so high levels of these omega-3 fatty acids in krill oil triacylglycerol was indicative of adulteration. Carbon (13C) NMR detected adulteration of krill oil with 10% or more anchovy oil, while TLC-FID detected levels as low as 1% adulteration with EPA ethyl esters. However, positional distribution of EPA and DHA, as determined using 13C NMR, was similar for both fish oil and krill oil, indicating that positional distribution cannot be used to show adulteration. Phosphorous (31P) NMR spectroscopy can show adulteration with low cost sources of phospholipid but was not useful for determining adulteration of krill oil with fish oil.