Effects of chemically or technologically treated linseed products and docosahexaenoic acid addition to linseed oil on biohydrogenation of C18:3n-3 in vitro.

ABSTRACT

Rumen biohydrogenation kinetics of C183n-3 from several chemically or technologically treated linseed products and docosahexaenoic acid (DHA; C226n-3) addition to linseed oil were evaluated in vitro. Linseed products evaluated were linseed oil, crushed linseed, formaldehyde treated crushed linseed, sodium hydroxide/formaldehyde treated crushed linseed, extruded whole linseed (2 processing variants), extruded crushed linseed (2 processing variants), micronized crushed linseed, commercially available extruded linseed, lipid encapsulated linseed oil, and DHA addition to linseed oil. Each product was incubated with rumen liquid using equal amounts of supplemented C183n-3 and fermentable substrate (freeze-dried total mixed ration) for 0, 0.5, 1, 2, 4, 6, 12, and 24h using a batch culture technique. Disappearance of C183n-3 was measured to estimate the fractional biohydrogenation rate and lag time according to an exponential model and to calculate effective biohydrogenation of C183n-3, assuming a fractional passage rate of 0.060/h. Treatments showed no differences in rumen fermentation parameters, including gas production rate and volatile fatty acid concentration. Technological pretreatment (crushing) followed by chemical treatment applied as formaldehyde of linseed resulted in effective protection of C183n-3 against biohydrogenation. Additional chemical pretreatment (sodium hydroxide) before applying formaldehyde treatment did not further improve the effectiveness of protection. Extrusion of whole linseed compared with extrusion of crushed linseed was effective in reducing C183n-3 biohydrogenation, whereas the processing variants were not different in C183n-3 biohydrogenation. Crushed linseed, micronized crushed linseed, lipid encapsulated linseed oil, and DHA addition to linseed oil did not reduce C183n-3 biohydrogenation. Compared with the other treatments, docosahexaenoic acid addition to linseed oil resulted in a comparable trans11,cis15-C182 biohydrogenation but a lesser trans10+11-C181 biohydrogenation. This suggests that addition of DHA in combination with linseed oil was effective only in inhibiting the last step of biohydrogenation from trans10+11-C181 to C180.