title: Effect of pH on biohydrogenation of polyunsaturated fatty acids and their Ca-salts by rumen microorganisms in vitro.
abstract: The influence of different pH values on the protection of Ca-salts of polyunsaturated fatty acids (PUFA) against ruminal biohydrogenation was investigated. Ca-salts were prepared from soya bean oil fatty acids (SOH) and incubated in vitro with rumen fluid at different pH values. Biohydrogenation of Ca-salts of the PUFA's and their corresponding free fatty acids in SOH was compared. Two series of incubations were carried out, a first series with pH varying between 6.9 and 5.5, while in the second series, a narrower pH range was studied (6.8-6.3). The experiments showed that between pH 6.9 and 6.3, Ca-salts of PUFA's are partly protected against biohydrogenation. Ca-salt of linoleic acid was protected to a greater extent than Ca-linolenate. Biohydrogenation of the salts is most probably due to dissociation of the solubilized Ca-salts. For efficient protection of Ca-salts of PUFA's against hydrogenation, maintenance of pH values above 6.3 will be necessary.
authors.affiliation: Department of Animal Production, University of Gent, MELLE, Belgium.
authors.forename: C J
authors.initials: CJ
authors.lastname: Van Nevel
authors.forename: D I
authors.initials: DI
authors.lastname: Demeyer
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006865:Hydrogenation; D008041:Linoleic Acids / Q000378:metabolism; D008042:Linolenic Acids / Q000378:metabolism; D008297:Male; D012417:Rumen / Q000378:metabolism / Q000382:microbiology*; D012756:Sheep / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D008042:Linolenic Acids; D002118:Calcium