Omega 3 Denaturing

[Klaus Urine]

I eat a lot of canned salmon. I understand that there is high heat involved in the canning process. As polyunsaturated oils are rendered trans-fats when too much heat is applied to them, I'm wondering whether anyone has any definitive answer as to whether there's any Omega 3s in canned salmon. Perhaps I'm just giving myself a huge intake of trans-fats...

[natron]

solid question. I've actually never thought about this? And I just made about 3 lbs of salmon salad for sandwiches yesterday???

[Dr Pangloss]

That would take quite a bit of energy and the right environment. You dont have anything to worry about. Everything i've read suggests canned salmon is loaded with omega3s.

here is an analysis of the omega 3 content in canned salmon and other canned fish. It''s fine:


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Arch Latinoam Nutr. 1996 Mar;46(1):75-7.
[Fatty acid composition and cholesterol content in naturally canned jurel, sardine, salmon, and tuna]

[Article in Spanish]
Romero N, Robert P, Masson L, Luck C, Buschmann L.
Departamento de Ciencia de los Alimentos y Tecnología Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile.
To obtain more information about fatty acid profile and cholesterol content of fat extracted from canned fish in brine habitually consumed in Chile, four different species Jurel (Trachurus murphyi), Sardine (Sardinops sagax), Salmon (Oncorhynchus kisutch) and Tuna (Thunnus alalunga) were analyzed. The GLC of fatty acid methyl esters showed that the main group of fatty acids belongs to polyunsaturated, being omega-3 family the more important. The principal representants were eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), with percentages between 5%-11% and 12%-22% respectively. Omega-6 family was represented mainly by arachidonic acid (AA) with percentages between 2%-4%. Cholesterol content was similar to the values found in other animal origen meats. The figures were between 41-86 mg of cholesterol per 100 g of edible product, Tuna in brine, was the product with the lowest content of cholesterol. The calculated amount of EPA, DHA and total omega-3 fatty acids indicated values between 95-604, 390-1163 and 609-2775 mg respectively per 100 g of edible product. Due these results is important to emphasize the consumption of this type of canned fish in brine, that they really represent a good dietary source of mainly polyunsaturated omega-3 fatty acids. The international recommendations indicate to increase the consumption of fish, due the beneficial effects described in relation with cardiovascular disease, which is the mean cause of death in Chile, country with a wide variety of marine origen foods, but with a contradictory answer about its consumption which is not incorporated in the current diet.

[natron]

quick question.

when food is processed, do the label claims get tested before the processing, or after?

I'm assuming after, which would again prove there is nothing to worry about.

[Dr Pangloss]

quick question.

when food is processed, do the label claims get tested before the processing, or after?

I'm assuming after, which would again prove there is nothing to worry about.

that was the point of the above post. they analyzed canned fish. that is, fish after it was canned.

as to your question: i would think it would be afterward, but i'm not sure.

[natron]

that was the point of the above post. they analyzed canned fish. that is, fish after it was canned.

as to your question: i would think it would be afterward, but i'm not sure.

Yeah, I've just never really thought about it. But with the laws I would assume the label claims are after processing etc.

[Klaus Urine]

That would take quite a bit of energy and the right environment. You dont have anything to worry about. Everything i've read suggests canned salmon is loaded with omega3s.

here is an analysis of the omega 3 content in canned salmon and other canned fish. It''s fine:


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Arch Latinoam Nutr. 1996 Mar;46(1):75-7.
[Fatty acid composition and cholesterol content in naturally canned jurel, sardine, salmon, and tuna]

[Article in Spanish]
Romero N, Robert P, Masson L, Luck C, Buschmann L.
Departamento de Ciencia de los Alimentos y Tecnología Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile.
To obtain more information about fatty acid profile and cholesterol content of fat extracted from canned fish in brine habitually consumed in Chile, four different species Jurel (Trachurus murphyi), Sardine (Sardinops sagax), Salmon (Oncorhynchus kisutch) and Tuna (Thunnus alalunga) were analyzed. The GLC of fatty acid methyl esters showed that the main group of fatty acids belongs to polyunsaturated, being omega-3 family the more important. The principal representants were eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), with percentages between 5%-11% and 12%-22% respectively. Omega-6 family was represented mainly by arachidonic acid (AA) with percentages between 2%-4%. Cholesterol content was similar to the values found in other animal origen meats. The figures were between 41-86 mg of cholesterol per 100 g of edible product, Tuna in brine, was the product with the lowest content of cholesterol. The calculated amount of EPA, DHA and total omega-3 fatty acids indicated values between 95-604, 390-1163 and 609-2775 mg respectively per 100 g of edible product. Due these results is important to emphasize the consumption of this type of canned fish in brine, that they really represent a good dietary source of mainly polyunsaturated omega-3 fatty acids. The international recommendations indicate to increase the consumption of fish, due the beneficial effects described in relation with cardiovascular disease, which is the mean cause of death in Chile, country with a wide variety of marine origen foods, but with a contradictory answer about its consumption which is not incorporated in the current diet.

Cheers for that. Interesting that they didn't even mention trans fats.

Also, I guess the canning process might vary a bit.

[Dr Pangloss]

Cheers for that. Interesting that they didn't even mention trans fats.

Also, I guess the canning process might vary a bit.

canning is a pretty standard process. there is no mention of conversion to trans fats in the literature. as with most molecules, omega 3s can be pyrrolized (burned) and thereby oxidized. i think that's what you're talking about. Oxidation. Because conversion to trans fat only involves changing the locus of the double bonds so that the hydrogens are on the opposite side of the planar double bond.

[Dr Pangloss]

here's another paper of interest.

cis/trans-Isomerisation of triolein, trilinolein and trilinolenin induced by heat treatment





References and further reading may be available for this article. To view references and further reading you must purchase this article.


Wakako Tsuzuki, a, , Reiko Nagataa, Ritsuko Yunokia, Mitsutoshi Nakajimaa and Tadahiro Nagataa

aNational Food Research Institute, Kannondai 2-1-12, Tsukuba, Ibaraki 305-8642, Japan



Received 16 July 2007;
revised 28 August 2007;
accepted 16 October 2007.
Available online 24 October 2007.



Abstract

To estimate the trans-fatty acid production of edible oils during the frying process, 1.0 g of triolein, trilinolein and trilinolenin, as representative oils, were heated at 180 °C for a defined period. The amounts of trans-fatty acids in heated triacylglycerols were quantitatively determined by gas chromatography after methylation. It was revealed that heating induced cis to trans-isomerisation of unsaturated triacylglycerols, and that trans-fatty acid amounts increased gradually, depending on the heating period. For example, trans-isomer amounts in triolein, trilinolein and trilinolenin (per gram) were 5.8 mg, 3.1 mg and 6.5 mg, respectively, after 8 h incubation at 180 °C. At that time, the contents of polar compounds contained in the heated triolein, trilinolein and trilinolenin were 22%, 27% and 31%, respectively. When triolein was heated under a N2 stream, neither trans-isomerisation nor polar compounds were detected. The addition of α-tocopherol (1.0%) to triolein significantly prevented not only lipid oxidation but also trans-isomerisation during heating. A commercially available vegetable oil was also heated under the same conditions as these model oils. Compared with the trans-isomerisation in model oils, the degree of trans-isomerisation in the edible oil was relatively low. Tocopherols in the oil would prevent not only lipid oxidation but also isomerisation. These results suggest that the geometric isomerisation of unsaturated fatty acids during heating accompanies lipid oxidation.

[Dr Pangloss]

canning is a pretty standard process. there is no mention of conversion to trans fats in the literature. as with most molecules, omega 3s can be pyrrolized (burned) and thereby oxidized. i think that's what you're talking about. Oxidation. Because conversion to trans fat only involves changing the locus of the double bonds so that the hydrogens are on the opposite side of the planar double bond.

the above publication corrects the notion expressed at the bottom of the quoted post above. i did not think this occured much with heat in the absence of further oxidation. Apparently it is a worry.

However,

turns out, there isn't much cis trans isomerization with heat in vegitable oil, as indicated above.... this is a very good indication that there would not be much with omega oils as well.

I think some whole foods people try to convince everyone food loses its value with cooking. It seems only slightly true.

[Dr Pangloss]

finally, a direct test of omega 3s after heating to at least 180 degrees C to deoderize. shows very little conversion:

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J Chromatogr A. 2006 Sep 29;1129(1):21-8. Epub 2006 Aug 7.
Analysis of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization.

Fournier V, Juanéda P, Destaillats F, Dionisi F, Lambelet P, Sébédio JL, Berdeaux O.
UMR FLAVIC Department, INRA, 17 Rue Sully BP 86510, 21065 Dijon, Cedex, France.
Addition of long-chain polyunsaturated fatty acids (LC-PUFAs) from marine oil into food products implies preliminary refining procedures of the oil which thermal process affects the integrity of LC-PUFAs. Deodorization, the major step involving high temperatures, is a common process used for the refining of edible fats and oils. The present study evaluates the effect of deodorization temperature on the formation of LC-PUFA geometrical isomers. Chemically isomerized eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as reference samples. Fish oil samples have been deodorized at 180, 220 and 250 degrees C for 3 h and pure EPA and DHA fatty acid methyl esters (FAMEs) were chemically isomerized using p-toluenesulfinic acid as catalyst. FAMEs prepared from fish oil were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC). Geometrical isomers produced by both processes were fractionated by silver-ion thin-layer chromatography (Ag-TLC) and silver-ion high-performance liquid chromatography (Ag-HPLC). The FAME fractions were subsequently analyzed by gas chromatography (GC) on a 100 m highly polar cyanopropylpolysiloxane coated capillary column, CP-Sil 88. Our results show that thermally induced geometrical isomerization appears to be a directed reaction and some ethylenic double bond positions on the hydrocarbon chain are more prone to stereomutation. Only minor changes were observed in the EPA and DHA trans isomers content and distribution after deodorization at 180 degrees C. The analyses of EPA and DHA isomer fractions revealed that it is possible to quantify EPA geometrical isomers by GC using the described conditions. However, we notice that a mono-trans isomer of DHA, formed during both chemical and thermal treatments, co-elute with all-cis DHA. This feature should be taken into consideration for the quantification of DHA geometrical isomers.

[Klaus Urine]

Thanks very much, Dr P, I appreciate it.

I wonder what the how hot the fish gets during canning.

[Dr Pangloss]

Thanks very much, Dr P, I appreciate it.

I wonder what the how hot the fish gets during canning.

180 degrees C is very hot. you have to pressurize, such as is done with canning to get this high with something like a meat in aqueous solution.

[Dr Pangloss]

I just checked. Patented processes for canning fish use temperatures lower than 180 C. About 130--140C under pressure.

[natron]

at that temp, it's must be a pretty quick process?

Salmon would over cook very quickly, not that this has to do with anything, just sayin