Conjugated linoleic acid production in fermented foods

Advances in Fermented Foods and Beverages. http //dx.doi.org/10.1016/B978-l-78242-015-6.00004 9 

Shingfield et al, 2008). The predominant isomer originally present in food was shown to be cis-9,trans-ll CLA that occurs together with trans-10,cis-12 and trans-1, cis-9 CL A, which are also present in minor but significant amounts. In contrast, commercial CLA preparations used for functional foods can contain similar concentrations of both enantiomers (Or-Rashid, AlZahal, McBride, 2011 Park, 2009 Wahle, Heys, Rotondo, 2004). 

The first discovered CLA precursor is linoleic acid (cw-9,ds-12 18 2). The double bond of linoleic acid present further for the carboxyl group can be translocated by cis- 2,trans- isomerase (Kepler Tove, 1967) and the resulting rumenic acid (cis-9,trans- CLA) is then hydrogenated by the reductase of Butyrivibrio fibrisol-vens to vaccenic acid (trans- l 18 1) (Hughes, Hunter, Tove, 1982). These steps occur relatively fast, whereas the hydrogenation of vaccenic add to stearic acid is 

The other pathway of the isomerisation of linoleic acid is provided by the action of cis-9,trans- 0 isomerase in the rumen (Griinari Bauman, 2006). The resulting trans-l9,cis-l2 CLA can be reduced to trans- 9 18 1 by Butyrivibrio fibrisolvens JWll (McKain, Shingfleld, Wallace, 2010). 

CLA can also be synthesised in the human colon. Some bacterial strains normally present in the human large intestine Lactobacillus, Propionibacteriim and Bifidobacterium species and some Clostridium-]ike bacteria) have been found to metabolise linoleic acid and form CLA that is converted further to tram-1118 1 in vitro. Vaccenic acid may be also a precursor of rumenic acid cis-9dram-ll CLA) in human tissues (Devillard, McIntosh, Duncan, Wallace, 2007). 

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Conjugated linoleic acid production in fermented foods... 

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