Analysis of alpha-linolenic acid biohydrogenation intermediates in milk fat with emphasis on conjugated linolenic acids.
Ruminal biohydrogenation of alpha-linolenic acid is not fully understood compared with that of linoleic acid. Some hypothetical intermediates, that is, conjugated isomers of alpha-linolenic acid (cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15 18:3) have never been reported to occur in ruminant fat. Therefore, milk fat was analyzed using a combination of techniques to characterize alpha-linolenic acid biohydrogenation intermediates. Tandem off-line argentation thin-layer chromatography and high-resolution gas-liquid chromatography using a 120-m highly polar, open tubular capillary column coated with 70% cyanoalkyl polysiloxane equivalent material was used for quantification. Structural characterization of fatty acids was achieved by gas-chromatography mass-spectrometry after synthesis of specific azo-derivatives. This study confirmed that minute amounts of alpha-linolenic acid biohydrogenation intermediates are present in milk fat. Routes involved in biohydrogenation of linoleic and alpha-linolenic acids in the rumen and subsequent endogenous metabolism of related biohydrogenation products are discussed.
Destaillats
F
F
Department of Food Science and Nutrition, Dairy Research Center (STELA), Université Laval, Sainte Foy, Québec, G1K 7P4, Canada.
Trottier
J P
JP
Galvez
J M G
JM
Angers
P
P
D000818:Animals; D005223:Fats / Q000737:chemistry*; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006865:Hydrogenation; D044243:Linoleic Acids, Conjugated / Q000032:analysis*; D013058:Mass Spectrometry; D008892:Milk / Q000737:chemistry*; D010080:Oxazoles / Q000032:analysis; D012417:Rumen / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000737:chemistry* / Q000378:metabolism*
D005223:Fats; D005231:Fatty Acids, Unsaturated; D044243:Linoleic Acids, Conjugated; D010080:Oxazoles; C502940:rumelenic acid; D017962:alpha-Linolenic Acid