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A simplified method to distinguish farmed (Salmo salar) from wild salmon: fatty acid ratios versus astaxanthin chiral isomers.

Megdal PA, Craft NA, Handelman GJ - Lipids (2009)

Bottom Line: We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement.Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples.GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon.

View Article: PubMed Central - PubMed

Affiliation: University of Massachusetts Lowell, Lowell, MA, USA. pmegdal@efasciencesinc.com

ABSTRACT
Mislabeling of farmed and wild salmon sold in markets has been reported. Since the fatty acid content of fish may influence human health and thus consumer behavior, a simplified method to identify wild and farmed salmon is necessary. Several studies have demonstrated differences in lipid profiles between farmed and wild salmon but no data exists validating these differences with government-approved methods to accurately identify the origin of these fish. Current methods are both expensive and complicated, using highly specialized equipment not commonly available. Therefore, we developed a testing protocol using gas chromatography (GC), to determine the origin of salmon using fatty acid profiles. We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement. Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples. The method is suitable for wide adaptation because fatty acid methyl ester analysis is a well-established procedure in labs that conduct analysis of lipid composition and food constituents. GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon.

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Two representative gas chromatograms of farmed and wild salmon with major fatty acids and the prominent 18:2n-6 peak for the farmed salmon
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Fig3: Two representative gas chromatograms of farmed and wild salmon with major fatty acids and the prominent 18:2n-6 peak for the farmed salmon

Mentions: Representative fatty acid profiles by GC of wild and farmed salmon are shown in Fig. 3. The elevated 18:2n-6 peak is highly distinctive and easily identifiable on the trace of the cultivated sample. Farmed samples may have lower 20:1n-9, but this fatty acid was not statistically significant (P = 0.07). The other fatty acid components are generally comparable between wild and cultivated salmon and are not statistically different. Also, there was a non-significant trend toward decreasing percent of several major fatty acids in cultivated salmon reflecting the presence of increased 18:2n-6 (see Table 1; Fig. 2). The 22:1n-11 peak (sometimes called cetoleic acid), which elutes at 26.8 min in Fig. 3, is more abundant in many of the wild samples than in the farmed samples, but exhibits a high variance between samples. The peak is present at low abundance in all the farmed samples (1–2%) and in some wild samples. This may reflect the fact that some of the wild-caught fish consumed copepods or other foods rich in 22:1n-11. Although of potential interest, this fatty acid cannot be reliably used for classifying the origin of the fish. Thomas et al. [27] also observed a much greater variance for 22:1n-11 in wild salmon than the other fatty acids reported in their study.Fig. 3


A simplified method to distinguish farmed (Salmo salar) from wild salmon: fatty acid ratios versus astaxanthin chiral isomers.

Megdal PA, Craft NA, Handelman GJ - Lipids (2009)

Two representative gas chromatograms of farmed and wild salmon with major fatty acids and the prominent 18:2n-6 peak for the farmed salmon
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2697370&req=5

Fig3: Two representative gas chromatograms of farmed and wild salmon with major fatty acids and the prominent 18:2n-6 peak for the farmed salmon
Mentions: Representative fatty acid profiles by GC of wild and farmed salmon are shown in Fig. 3. The elevated 18:2n-6 peak is highly distinctive and easily identifiable on the trace of the cultivated sample. Farmed samples may have lower 20:1n-9, but this fatty acid was not statistically significant (P = 0.07). The other fatty acid components are generally comparable between wild and cultivated salmon and are not statistically different. Also, there was a non-significant trend toward decreasing percent of several major fatty acids in cultivated salmon reflecting the presence of increased 18:2n-6 (see Table 1; Fig. 2). The 22:1n-11 peak (sometimes called cetoleic acid), which elutes at 26.8 min in Fig. 3, is more abundant in many of the wild samples than in the farmed samples, but exhibits a high variance between samples. The peak is present at low abundance in all the farmed samples (1–2%) and in some wild samples. This may reflect the fact that some of the wild-caught fish consumed copepods or other foods rich in 22:1n-11. Although of potential interest, this fatty acid cannot be reliably used for classifying the origin of the fish. Thomas et al. [27] also observed a much greater variance for 22:1n-11 in wild salmon than the other fatty acids reported in their study.Fig. 3

Bottom Line: We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement.Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples.GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon.

View Article: PubMed Central - PubMed

Affiliation: University of Massachusetts Lowell, Lowell, MA, USA. pmegdal@efasciencesinc.com

ABSTRACT
Mislabeling of farmed and wild salmon sold in markets has been reported. Since the fatty acid content of fish may influence human health and thus consumer behavior, a simplified method to identify wild and farmed salmon is necessary. Several studies have demonstrated differences in lipid profiles between farmed and wild salmon but no data exists validating these differences with government-approved methods to accurately identify the origin of these fish. Current methods are both expensive and complicated, using highly specialized equipment not commonly available. Therefore, we developed a testing protocol using gas chromatography (GC), to determine the origin of salmon using fatty acid profiles. We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement. Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples. The method is suitable for wide adaptation because fatty acid methyl ester analysis is a well-established procedure in labs that conduct analysis of lipid composition and food constituents. GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon.

Show MeSH