Branched-chain fatty acid

Branched-chain fatty acids (BCFA) are usually saturated fatty acids with one or more methyl branches on the carbon chain.^[1][2] BCFAs are most often found in bacteria,^[2] but can be found in nattō,^[3] dairy,^[4] vernix caseosa of human infants and California sea lions^[5] where they may play a role in fostering the development of their intestinal microbiota.^[1] Another waxy animal material containing BCFAs is lanolin.^[2]

Chemical structures of 13-methyltetradecanoic acid (top) and 12-methyltetradecanoic acid, two branched chain fatty acids found in bacteria

Branched chain fatty acids are considered to be responsible for the smell of mutton^[6] and higher content causes consumers to dislike the smell of lamb meat.^[7] Branched-chain fatty acids are synthesized by the branch-chain fatty acid synthesizing system.

Plants and specialised metabolites. Branched-chain fatty-acid biosynthesis also occurs in plants. In several plant lineages (notably Solanaceae and Capsicum spp.) branched-chain acyl groups derived from valine, leucine or isoleucine are incorporated into specialised metabolites such as acyl sugars and capsaicinoids; transcriptomic, biochemical and reverse-genetics studies have identified the relevant branched-chain keto-acid / branched-chain acyl-CoA enzymatic steps and plant genes required for production of these branched-chain acyl donors in glandular trichomes and in the placenta of Capsicum fruits.^{[8][9][10][11]}