Select Science recently interviewed Professor Gene S. Hall, who leads a research team in the Department of Chemistry and Chemical Biology at Rutgers University in New Jersey, USA. They are detecting fraudulent fish oil and their work includes the Pearl FTIR accessory.
Gene spoke to Select Science about elements of his work surrounding the identification of fraudulent fish oil, specifically in nutritional and dietary fish oil supplements. For this work, Gene utilized techniques including Fourier-transform infrared spectroscopy (FTIR), GC-MS, energy dispersive X-ray fluorescence (EDXRF), plasma mass spectrometry (ICP-MS), C-12/C-13 isotope ratio fingerprinting methods and Raman spectroscopy.
Generally consumed to supplement a diet with the same omega-3 fatty acids as eating actual fatty fish (such as tuna, anchovy, salmon and menhaden), some fish oil supplements on the market don’t actually contain the same nutritional value they might imply. Gene Hall is working to discover new techniques to enable the efficient analysis of these supplements, so that industrial bodies such as the FDA may more easily detect food fraud.
Professor Gene Hall of Rutgers University
In the interview with Select Science, Gene discussed how products mislead the customer on their nutritional value.
Many of the products on the market that say they contain fish oil, do not actually contain omega-3 fatty acids in their natural triglyceride form… Many of the fish oil products on the market today say they are double or triple-strength, or ‘pharmaceutical grade’ but, beginning in 2016, the Food and Drug Administration (FDA) stated that terms like these – that characterize the strength of the nutrients ‘omega-3 fatty acids’ – cannot be used on fish oil dietary supplements’ labels.
FTIR spectroscopic testing included the use of Specac’s Pearl liquid transmission accessory to analyze the fish oil esters and differentiate between synthetic fatty acid ethyl esters and natural fish oil that has been expressed from a fish and has not been chemically altered.
For this work Gene’s team followed the United States Pharmacopeia (USP) reference fish oil standard (menhaden oil, Cat. No. 1381200) and definitions of various omega-3 sources as described in the 2016 GOED Technical Guidance Documents.
Results of the analysis
Looking at over 3,000 omega-3 products, the team found many supplements containing synthetic fatty acid ethyl esters, which Gene reminded Select Science can be hazardous to pregnant women due to the ethanol they contain as a by-product of hydrolysis.
Spectra of a product described as ‘virgin Alaskan salmon oil’ vs. salmon oil squeezed from a fresh farmed-raised salmon fillet. Diagnostic 1036 cm-1 ethyl ester band is exhibited in the dietary supplement. Source: SelectScience®
Using the Pearl for FTIR analysis of Fish Oil
Gene used the Pearl with different window pathlengths, 25, 50 and 100 microns. This allowed the testing of different specific vibrational diagnostic bands in the sample, such as 100 microns being used for fast and sensitive analysis of the 966 cm-1 vibrational band. This band is diagnostic of trans-isomers in the sample using AOCS Cd 14-95 or AOAC 965.3 methods, as well as differentiating between natural TAG and rTAG products (based on enhanced sensitivity of the O-H stretch band due to incomplete reacted DAGs and MAGs).
The professor told Select Science that using the Specac Pearl streamlined the process.
The nice thing about the Pearl is that it’s very simple to use, it’s got great sensitivity and it’s easy to clean up – you can get your results in a matter of seconds, because you can see the infrared spectra and you can easily identify what is natural fish oil and what is not.
Check out this video of the Pearl being used to analyze another viscous sample, engine grease.
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