Fingerprinting Krill Oil by ³¹P, ¹H and ¹³C NMR Spectroscopies

Abstract

The detailed analysis of krill oil is of importance to be able to differentiate other oils, identify adulterated products, and provide the highest quality associated with its beneficial health effects. The objective of this study was to demonstrate the usefulness of the combination of 31P, 1H and 13C nuclear magnetic resonance (NMR) spectroscopies to characterize the krill oil profile. It was found that in contrast to fish oil, where eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) fatty acids are found in triacylglycerol, krill oil is characterized by a more asymmetric fatty acid distribution with a higher polyunsaturated fatty acids PUFA content in the sn‐2 position of phospholipids and lower amounts in triacylglycerol. Besides the typical asymmetric fatty acid composition, several other markers were investigated for krill oil origin test. The validation of the 31P NMR spectroscopic method regarding major phospholipid species was performed according to the Good Laboratory Practice (GLP) and International Council for Harmonisation (ICH) guidelines. The method was characterized by high sensitivity, accuracy, and reproducibility. Interlaboratory testing showed satisfactory robustness regardless of the type of NMR equipment used by different laboratories. High‐resolution NMR spectroscopy has proven to be a convenient and exact method for providing a characteristic fingerprint of krill oil. By this technique, clear distinctions to other oils can be made through qualitative and quantitative analysis of krill oil.

Nuclear Magnetic Resonance (NMR) Spectroscopy in Food Science: A Comprehensive Review

“…Because of the magnetic properties of phosphorus nuclei, 31 P NMR analysis is characterized by high resolution and sensitivity. Most of the compounds of interest do not bear phosphorus on their structure, with the exception of phospholipids (Burri, Hoem, Monakhova, & Diehl, ); however, phosphorus can be easily added using a phosphytilation reaction, where compounds with labile protons react with a phosphytilated agent and the phosphytilated products can then be determined by their signals (Hatzakis & Dais, , ; Spyros, Philippidis, & Dais, ). More details about this approach can be found in the following publications (Dais & Hatzakis, ; Spyros & Dais, , 2009).…”

Higher omega-3 index after dietary inclusion of omega-3 phospholipids versus omega-3 triglycerides in Alaskan Huskies

“…A typical omega-3 source is fish oil, where the omega-3 PUFAs are bound to triglycerides (TGs), but more recently also products from krill have been included in diets for pets [ 7 , 8 ]. Krill meal is made from Antarctic krill ( Euphausia superba ) to provide a mix of proteins and fat, the latter being characterized by a high content of omega-3 PUFAs bound in PLs [ 9 ].…”

Seafood Phospholipids: Extraction Efficiency and Phosphorous Nuclear Magnetic Resonance Spectroscopy (31P NMR) Profiles

“…Some reports have associated dietary PL with unique health benefits (Schuchardt et al, 2011;Tou, Jaczynski, & Chen, 2007). Commercial fish oils consist of TAG (or in some cases ethyl esters) (Killeen, Marshall, Burgess, Gordon, & Perry, 2017), whereas commercial krill oils are high in PL (Burri, Hoem, Monakhova, & Diehl, 2016;The United States Pharmacopeia Convention, 2014). However, the PL content of krill oil depends heavily on the extraction method used: Supercritical CO 2 extraction yields oils with almost no PLs (Yamaguchi et al, 1986), but the same solvent, mixed with a polar cosolvent (20% ethanol is used commercially) extracts oils that contain 28-52% PL (Burri et al, 2016;Catchpole, Moreno, Montañes, & Tallon, 2017;The United States Pharmacopeia Convention, 2014).…”