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Effect of chemical form, heating and oxidation products of linoleic acid on rumen bacterial population and activities of biohydrogenating enzymes

Kaleem, Muhammad and Enjalbert, Francis and Farizon, Yves and Troegeler-Meynadier, Annabelle Effect of chemical form, heating and oxidation products of linoleic acid on rumen bacterial population and activities of biohydrogenating enzymes. (2013) Journal of dairy science, 96 (11). 7167-7180. ISSN 0022-0302

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Official URL: http://dx.doi.org/10.3168/jds.2013-6768


Heating polyunsaturated fatty acids (PUFA) produces oxidation products, such as hydroperoxides, aldehydes and oxypolymers, which could be at least partly responsible for modification of PUFA rumen biohydrogenation (BH). Three in vitro experiments were conducted to investigate the effects of linoleic acid (cis-9,cis-12-C18:2) oxidation products on BH. In the first experiment, we studied the effects of free linoleic acid (FLA), heated FLA (HFLA, at 150°C for 6h), triacylglycerols of linoleic acid (TGLA), heated TGLA (HTGLA, at 150 °C for 6h), 13hydroperoxide (13HPOD), trans-2decenal (T2D), and hexanal (HEX) on BH in vitro after 6h and 24h of incubation. In the second experiment, aldehydes differing in chain length and degree of unsaturation (pentanal, hexanal (HEX), heptanal, nonanal, T2D, trans-2,trans-4-decadienal (T2T4D)) were incubated in vitro for 5h in rumen fluid. In the third experiment, 9hydroperoxide (9HPOD), 13HPOD, HEX, or T2T4D were incubated for 1h in rumen fluid inactivated with chloramphenicol to investigate their effects on enzyme activity. In experiment 1, heat treatment of TGLA generated TGLA oxypolymers, did not affect cis-9,cis-12-C18:2 disappearance, but it decreased BH intermediates, especially trans-11 isomers. Heating FLA decreased cis-9,cis-12-C18:2 disappearance and cis-9,trans-11-CLA and trans-11-C18:1 production. HEX, and T2D did not affect cis-9,cis-12-C18:2 disappearance and barely affected production of BH intermediates. The bacterial community was affected by 13HPOD compared to LA and HLA, in parallel with an increase in trans-10 isomer production after 6h incubation. After 24h incubation, it decreased trans-11 isomer production, but to a lesser extent than HFLA, In experiment 2, some weak but significant effects were observed on BH, with no relation with chain length or degree of unsaturation of aldehydes; the bacterial community was not affected. In experiment 3, 9HPOD inhibited Δ9-isomerization while Δ12-isomerization was inhibited by both 9HPOD and 13HPOD. It was concluded that oxypolymers did not affect cis-9,cis-12-C18:2 disappearance. Heating both esterified and free cis-9,cis-12-C18:2 greatly altered the Δ12-isomerization. Aldehydes had few effects. Hydroperoxides would be at least in part responsible for the effects of fat heating: 13HPOD increased trans-10 isomer production, probably by affecting the bacterial community, and decreased trans-11 isomer production by inhibiting the Δ12-isomerase activity whereas 9HPOD inhibited both isomerases.

Item Type:Article
Additional Information:Thanks to American Dairy Science Association editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Journal of Dairy Science website : http://www.sciencedirect.com/science/journal/00220302
Audience (journal):International peer-reviewed journal
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Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
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Deposited On:23 Jan 2015 14:51

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