GLOBAL – Compound-specific stable isotope analysis (CSIA) could be the solution to accurately characterize fish oil hence detect fish oil fraud.
Fish oil varies depending on its source: fish from different regions—even within the same species—have different oil compositions, and, understandably, different price points depending on the quality.
Individuals and illicit organizations are exploiting the growing demand by circulating adulterated, mislabeled products with sub-standard fish oil and/or misrepresented product origin for financial gain.
Traditional food integrity techniques can’t accurately distinguish the origin of fish oils from the same species, say study authors David Psomiadis and Mario Tuthorn.
According to the authors, the existing approaches to determine fish oil authenticity, including gas chromatography-mass spectrometry (GC-MS) fatty acid profiling and untargeted fingerprint determination by spectroscopic techniques such as nuclear magnetic resonance (NMR) and near-infrared (NIR), are based on the compositional characteristics of the oils.
While these compositions are important to understand, they do not reflect significant regional and geographic parameters. Yet gaining clarity on the geographical origin of fish oils from the same species is vital because the source of the fish oil can have significant financial implications, they note.
In particular, label claims that fish oils are derived from a certain geographical region can add value to the product.
Confirming the fish oil origin also verifies traceability of the product and contributes to other important label claims including sustainability, health and safety. Therefore, knowing the origin of the fish oil and its authenticity helps to identify fraudulent practices that are used to boost product value.
How CSIS detects fraud
Fatty acids consist almost entirely of carbon and hydrogen. In fish, the natural variation of the isotopic ratios of these elements is influenced by the feed, the environment and the local habitat of a given population. CSIA can enhance fish oil testing by determining the stable isotopic values of individual fatty acids. Since isotopes vary with differing dietary sources, geographical regions of origin can be determined, even within the same species.
Recent advances in GC-IRMS allow the technique to provide the separation accuracy and detection resolution required to distinguish between different carbon and hydrogen isotopes in compositionally equivalent fatty acids, by CSIA.
GC-IRMS works by separating compounds using gas chromatography, then analyzing carbon and nitrogen isotope fingerprints by combustion, and oxygen and hydrogen isotope fingerprints through pyrolysis. This approach enables the acquisition of isotopic information for each individual compound in the sample.
To further improve the capability of GC-IRMS, the set-up can be coupled to a single quadrupole mass spectrometer—GC-MS-IRMS—to allow structural determination and identification of compounds.
With the hybrid system, the flow from the GC column is separated into two parts: the majority continuing for IRMS isotope analysis, with a minor portion for MS compound identification.
The innovative design does not impact IRMS sensitivity, thereby gaining structural information without compromise. These system attributes mean that GC-MS-IRMS can determine the structure and isotope ratio of each fish oil compound. Using this method, analysts can generate accurate (close to the absolute value), repeatable and reproducible results.
Health benefits accelerate market growth
As consumers become more aware of the health benefits of incorporating fish oil into their diets, such as lowering blood pressure and helping prevent heart disease. the demand for the commodity continues to grow.
Fish oil is packed full of heart-friendly omega-3 fatty acids, including the functionally important docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
As such, many companies are increasing their investments in providing high-quality fish oil supplements, such as those with value claims including single species, designated geographical origin, sustainability practices and traceability.
The industry was worth USD 11.95 Billion in 2021 and is expected to reach a value of USD 17.64 Billion by 2028—a CAGR of around 6.7%, as reported by Food Safety Tech.
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