Polymers of triglycerides generated during heating of fat do not protect linoleic acid from ruminal biohydrogenation

Heating fats often induces a decrease of cis-9, cis-12 C18:2 and cis-9, cis-12, cis-15 C18:3 biohydrogenation (BH) in vivo (Gonthier et al. 2005), in situ (Troegeler-Meynadier et al. 2006) and in vitro (Prive et al. 2010). This is of interest because it could increase polyunsaturated fatty acids (PUFA) content of ruminant products. Temperature and duration of heating of sunflower oil affect ruminal BH of PUFA, in part due to peroxide value (Prive et al., 2010). Our hypothesis was that polymers of triglycerides (TG), formed during heating of TG but not of free FA, could be responsible for partial protection of PUFA from BH.