Studies on monoene fatty acid isomers in hydrogenated fish oils

An analytical study of the geometrical and positional isomerisation of the monoenoic acids of partially hydrogenated fish oil is presented. The results showed that the monoene fatty acids of chain lengths 16, 18, 20 and 22 consisted of 75% in the trans ‐form and 25% in the cis ‐form. The double bonds were distributed symmetrically over the chain length, with well defined maxima in position Δ‐9 for the fatty acids of chain length 16 and 18, and in position Δ‐11 for the fatty acids of chain length 20 and 22. Trans ‐ and cis ‐isomers showed the same positional distribution. Geometric as well as positional isomerization seemed to have reached an equilibrium state in the sample investigated.