Short communication: rearrangement of rumenic Acid in ruminant fats: a marker of thermal treatment.
Rumenic (cis-9,trans-11 18:2) acid is the main conjugated linoleic acid (CLA) isomer in milk and other ruminant fats. Anhydrous regular and high-CLA butterfats were heated at 200 degrees C for 2, 4, and 6 h under atmospheric conditions. [1,5] Sigmatropic isomerization of rumenic acid occurred, resulting in the formation of trans-8,cis-10 18:2 acid, as determined by mass spectrometry of its 4,4-dimethyloxazoline derivative. Rate of isomerization was monitored by gas-liquid chromatography, using a 120-m capillary column coated with 70% equivalent cyanoalkylpolysiloxane polymer, and reaction was of first order. Furthermore, [1,5] sigmatropic rearrangement product analysis can be used as an indicator of heat treatment of natural fats and oils containing CLA.
Destaillats
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Department of Food Science and Nutrition, and Dairy Research Center (STELA), Quebec, Canada, G1K 7P4.
Japiot
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Chouinard
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Arul
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Angers
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D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas; D005223:Fats / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000032:analysis* / Q000737:chemistry; D008055:Lipids / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry
D005223:Fats; D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D008055:Lipids; D010080:Oxazoles; C046938:9,11-linoleic acid; C057549:4,4-dimethyloxazoline; C013698:tallow